LifeOnWry, I like how you handled that. For curiosity’s sake, how did the QB respond to it? Or did he not at all?
Over the years I have met many celbs, usually as part of my business. Most of them are really cool if you mention that you enjoy their work. The big exception was William Shatner who hates if anyone mentions Star Trek.
I met John Larroquette (Dan Fielding in Night Court) while shopping. I asked him for a moment of his time, and thanked him for all the laughter over the years. He was very gracious and would have talked to me longer, but I cut it short.
Nice guy, good actor.
I’ve seen several celebrities in passing, considering I live in L.A. I’ve always left them alone, because if they’re doing everyday things (travelling, shopping, walking around), then I’m sure they don’t want to be bothered.
Then again, I’m another one that has had a celebrity approach me, and that’s a whole other story.
In an airport? I’d leave him alone.
Now, if we were in the same bar and I’d had a few too many? Um…ideally, leave him alone, but we don’t live in an ideal world, now, do we?
If it were someone whose work I totally adore (granted, there are few of those, and many of them aren’t as famous as they should be), I would approach him/her. If I worked that hard, with such great results, you betcher sweet ass I would want people to compliment me on it! Not to the point of harrassment, but a brief “I love your work… can I have your autograph, please?” would always be welcome in my book.
I usually leave them alone. I came face to face with Willie Nelson at an airport once, I said, “Hi Willie”. He answered back with a, “Hello, how are you?”. So I figured it was OK to talk for awhile. But generally if I see a celeb sitting somewhere eating, reading, or just minding their own business, I figure they don’t want to be bothered.
I have to agree, be especially cautious around rock stars and pro sports stars, I have seen many of these guys be total jerks, even to children.
Well…mostly I’d leave them alone. BUt if I saw James (yes,James Marsters and I are on a first name basis now…) I really, really dont think I’d have the self control to avoid approaching him. But on the other hand, I’m usually struck dumb and paralyzed by the sight of him, so it’s probably a moot point.
Leave 'em alone.
My dad has had many conversations with celebrities at the various marinas on the east end of Long Island. He’ll chat with anyone who is hanging around the docks, and my dad is definitely fun to talk to. Then somewhere along the way, he’ll realize that the guy he is chatting with is a big celebrity. Or someone will point it out to him later. Even if he does figure out who he’s talking to, he never mentions that he knows who they are. He figures that bringing up the person’s celebrity status would just ruin a conversation about something much more interesting and important than any celebrity: boats. 
I usually leave them alone. In fact, when I’ve visited movie or TV sets (that’s happened a few times—I have some friends who worked on the shows) I sometimes had to be dragged (by my friend who worked on the show) to ask for an autograph. I just feel weird disturbing them.
However, I did “impose” on Roddy McDowall and Jeremy Brett one time (well, two different incidents) and even though I strongly doubt that they minded that much (all I did was gush like a fool), I still feel embarrassed about it.
I’m a leave 'em alone kind of guy. Upon occasion I’ve sent an e-mail to someone I particularly admire (though I don’t know if Eddie Coan, Lawrence Block or Nancy A. Collins quite qualify as celebrities) and received a reply, but that’s not the same thing. I figure if they wanted you to know they were there, then they’d have had somebody let you know they were there. Otherwise, they’re probably busy and any chance they get to avoid hearing the same thing from another random person is probably something they’d appreciate.
There is one exception to my policy. If I ever encounter Tom Hanks, I will (security permitting) be the gushing fanboy. I will run up to him and pump his hand and tell him how much I loved his work. Then I will lock eyes with him, lower my voice, and ask him what Peter Scolari is really like.
On the rare occasions when this has happened to me, I’ve always left them alone. It seems the polite thing to do.
It depends on the situation.
If they were sitting alone reading the paper, I’d leave them alone.
If we were next to each other in line, I might be tempted to say something.
And,. like Quasimodem mentions, if it was Carrot Top, I’d kick his ass “down the middle”.
I was once having a beer with, among others, a well known musician when suddenly some idiot came up and shouted “Hey, you’re <insert name>! Do you remember the gig you had at the <insert place name> rock festival 10 years ago bla bla bla bla”. When he finally had gone someone said “I just don’t understand how you can stand people like that” and got the answer “It’s all right. I’ve got used to it”.
That said. Peple need their privacy, even if they happen to be celebrities.
Not in an airport, no.
I’m usually grumpy if I’ve been travelling for a while, feeling unclean, wanting to go home, delayed flights, etc. They probably feel a bit the same. If it were someone I had admired my whole life, I might approach them long enough to say, “I don’t wish to disturb you, just come up to you long enough to say thank you for making a difference in my life. I admire you. Enjoy your day.”
And leave.
But that would be rare, because, like I said, airports are sucky places to have to be stuck anyway.
I’d just leave them alone. I can’t imagine what it must be like to be bothered everytime I go into public.
Any time I’ve seen a celebrity anywhere I’ve left them alone. Recently I saw Gladys Knight in an airport being very gracious to people who don’t share that philosophy.
When living in San Francisco, ran into Robin Williams and family pretty regularly (once with George Lucas - we were waiting for the same flight down to L.A.). Left 'em alone.
Ran into the gold-medal figure-skating champ Scott Hamilton in an airport - gave him a quarter so he could buy a newspaper. He wanted to talk a bit, so we did. Nice guy. For that matter, now that I think about it, I sat next to a woman figure skater on a plane - a pairs skater, at the time she was engaged to some Canadian guy skater named Rocky something, I think - we talked the whole flight - I think she was refreshed that I didn’t know who she was per se. I think I was refreshed about talking to a beautiful with amazing legs wearing shorts in the chair next to me!!
Spoke to Clarence Clemmons after running into him at a small club show we had both gone to see. Nice guy. The funny part is that I had seen him go in and used his name to claim free admission on the guest list (I was a fast talker in my day) so the fact that he ended up standing next to me and shaking my hand validated the con job I had used. It was pretty funny at the time.
There’s more, but my tendency is to give them space unless there is a logical reason to talk, or we are standing next to each other and it is socially appropriate.
I’m so bad connecting faces and names, I could well have ignored many celebrities over the years. As for now, I do all my flying on Southwest - I doubt that the rich and famous want to be in yet another cattle call. 
But I wouldn’t approach, and if noticed, I hope I could manage a smile and a “hi” before going on my way.
For me it would depend on the level of fame of the celebrity and my estimation of their talent. I saw my musical idol Robyn Hitchcock at a coffeeshop several hours before a show. Of course I said a brief hello. I figured maybe one out of a couple thousand people in the US even knew who he was. I could be reasonably certain that he didn’t get that all the time.
On the other hand I was in the same store with Sinead O’Connor at the height of her fame in Georgetown. She seemed to be trying to be nice, but she was practically surrounded. I figured the last thing she needed was another gawker.