We all have brain farts. This guy may need to try to put 100 names with faces.
“Excuse me” to get your attention is what he should say if he spaced your name.
I would try not to read to much into it, but simply say, "It’s [your name here] how are you today Mr. [Boss]. It’s a little assertive, but puts a foot forward.
Welcome to the boards, Lonnie! I think this is excellent advice.
It could be worse. My dad refers to his boss as “that little black girl,” even though she’s in her 60s, and his superior, whom he actually respects and likes. Oh, dad.
I still have people occasionally call me “young lady” - I’m 60 and retired, fercryinoutloud!! It’s not flattering - it was *never flattering! As was mentioned upthread, it’s a term one might use to scold a sassy child or teen. Lots of good suggestions here - surely one will work. I need to remember them, because my gut reaction is usually "F#k off!!" But I’m too classy to say that. 
I work in IT support and get called “lad” or one of the “lads” all the time. HATE IT. It’s just another way for the co-workers to demean and subjugate me.
I get called ‘young man’ a lot these days. I’m closing in on 60. It’s a way some people have of trying to be nice, acting like I’m young when I’m not, that comes off odd to me. I mostly get it from older people, both male and female. Every now and then I’ll get it from some guy that is probably a few years younger than me and I have to wonder if I look particularly old that day, since the ‘kids’ are trying to make me fell less bad about my age.
For the OP, if you don’t like what people call you, you just tell them calmly what you like to be called, whatever that is. Whether it’s a pronoun you want used, a family name, nickname or anything else. It is on them to respect your wishes in the future.
Be glad he doesn’t call to you by saying, “hey, you with the face!” 
Seriously though, I agree. I didn’t even have to hear the context to think that “young lady” in the workplace is disrespectful and condescending.
If someone called me by something similar (“young man”?), I too wouldn’t like it. However, I would likely shrug it off, as I don’t feel it’s enough of an injustice to warrant any specific action. The exceptions to this rule are when the person does it in front of others (such as in meetings or on calls) or when it’s with a workmate with whom I’m closely or frequently working (like a teammate or manager). In either of those situations, I would feel uncomfortable enough to take action.
I’d be content to let this sleep until may the next time he did it, but I’m concerned his next time will happen at a high-level meeting that I’ll be running next week. So now I’m faced with taking this issue to him now–and possibly come off like I’m making a fuss over a day-old breach in business decorum but at least the problem will be nipped in the bud–or risk having him diminish my status in front of executives, directors, and senior scientists. And then, if that happens, I’ll be in a second catch-22: let the whole thing slide so as not to cause a scene that detracts from the meeting (but look weak and unassertive) or correct him in front of his peers and mine (which will make him look bad).
Ugggh, I hate crap like this.
I say wait until next time: if hearing an old man inappropriately call you “young lady” will truly make executives/directors/senior scientists think less of you, you have bigger issues at work. 
It will reflect more poorly on him than on you. If he does say it in front of them, just smile and give him a patronizing look: then address it with him in private afterwards.
Along these lines, an older gentleman working checkout at the grocery store called me “girl” the other day (i.e., he greeted me with, “Hey, girl!”). I was a little taken aback – I’m 42 – but I decided to let it slide. If I wind up in his line again and get the same greeting, though, he’s getting called “boy” in return. grin
He sounds incredibly condescending.
Call him sir, and/or Mr. [whatever his surname is].
Completely and totally inappropriate.
If a courtly older gentleman called me “young lady” in a non-work situation, then context would matter. There is no work situation where this would be appropriate.
Good one. I like something like this or the “we’ve worked together long enough…” approach.
Welcome to the boards, Lonnie.
A ha ha!!! This, a thousand times this! And please post it to youtube.
You’re right to be offended. But you don’t want to piss off a senior exec, either. Next time he calls you young lady, work in a politely-worded reply: “Please, call me Alice.” (or whatever your name is)
He shouldn’t be calling you “young lady” but he also meant no harm by it (other than to make it clear he doesn’t consider you an equal). He thinks he was being charming (lol ya I know, old guys are weird like that). The good news is that he likes you and that’s what you should take away from this.
I never address someone as “young lady” (or “young man”) to her (or his) face.
If I am addressing someone else about her, I will refer to her as “that young lady” or “this young lady” (but only if I do not know her name).
Not to put you on the spot, but do you really believe that being liked is what matters the most in this interaction? If being liked means he has to relate to me as though I’m a juvenile, I would actually prefer that he not like me.
The part in bold shouldn’t be parenthesis, since it’s the source of my beef. There are acceptable ways for people to throw their weight around and there are unacceptable ways.
Yes it’s wrong. Being from the south, I more frequently had a problem with ladies calling me Sweetie, Honey, or Sugar. Blach! I’ve always felt it inappropriate to address people you work with through any terms of endearment regardless of how nice and friendly they’re trying to be. That’s too personal for professional relationships and better left for family. I don’t even want a cheap diner waitress doing it.
Whenever my Mom called one of my sisters “young lady,” I made myself scare but stayed within hearing distance. There was trouble brewing.
Of course being liked is the most important thing. You’re a girl. Duh.
Aha! Look at him,say “Am I in trouble,Sir? Whenever my mom called me that,I was!”
Anytime he calls you that,repeat… Same tone,same everything…
I understand that it is annoying but he might be using that term in an endearing way. I work with a few people that are about 30 years older than me (all male) and they cannot help but treat me a bit differently because I am a younger female. Whilst it is strange at times, I do not take offence at all as I know it is just their way of trying to interact with someone that they probably feel a bit uncomfortable around. Perhaps at your next birthday you could make a comment about getting old and feeling like a middle aged lady now. Something that is pointed but playful and not too direct.
I don’t have a filter that keeps me from staying political in these situations. It wouldn’t matter what his rank was compared to mine. The first time he said something like, “Good morning, young lady,” to me, my automatic answer without thinking would be, “Well, hello to you, too, little fella!”
Probably why I never quite fit in when I worked at a schmancy bank.