For the record, handsome, are you claiming that you knew this by magic/supernatural powers/telepathy, or do you think you did it through ordinary, natural means, as discussed above?
Do you believe in supernatural powers?
It probably a combination of “natural” (seeing, hearing, smelling) and “supernatural” (sensing her brainwaves).
Brainwaves? What the heck are brainwaves?
Subtle changes in “electric” and “magnetic” fields that result from neurons firing in the brain, thought to be one possible explanation for telepathy, telekenisis, clairvoyance, and other “psychic” phenomenon.
Why would one need an explanation for phenomena that have not even been demonstrated to exist?
Show me evidence for “psychic” phenomena that is not anecdotal in nature, and then we can discuss possible explanations.
Oh, those brainwaves. Are you sure you weren’t being being watched by the Jello[sup]®[/sup] she was eating?:
There are two flaws in that explanation.
First, your peripheral vision does not contain a sufficient concentration of cones or rods to make out fine detail. You could tell that a person was there, but you couldn’t see details such as where their eyes were pointing. In order to see that much detail, they’d have to be pretty close to the center of your field of vision, and that’s not likely to stay subconscious.
Second, you said “a minute or two later”. Well, a minute or two later, any subconscious cues you may have picked up on are no longer valid. You don’t know where the person is looking now, even if you did a few minutes ago.
In order to accurately tell, right now, that someone is looking at you, you’d need some sort of psychic ability. Either that, of you’d need to look right at them and somehow not consciously see them. And please note that I am not not talking about simply knowing that someone is there (which can easily be accounted for by things like peripheral vision), but knowing that they are looking at you.
One line from the OP cought my eye:
Notice that these people think of it as an “ability”. To me, that implies something more than just subconscious cues, although I suppose it’s open to interpretation.
For one thing, my experience in the DMV. Also, I had a big night in Reno back in '91. From the moment I walked into the Sundowner, I knew it was my night. Somehow, I visualized the dice coming up in my favor, and they did again and again. I cleared over 5 thousand dollars that night. It never happened like that since then but they say “psychic” events can be unpredictable.
That’s a perfect example of selective memory. you’ve probably gambled many times, and I’d bet odds you’ve often “visualized the dice coming up in your favor”, but since they didn’t you promptly forgot about it. Naturally you recall the one time you did win after such a “vision”. No surprises here.
Next.
No, something special happened that night. And it is well known that many people have had “psychic” experiences.
Bullshit. Name one.
Jesus?
Well, if Jesus will come back like he’s supposed to, he can collect the $1 million JREF prize, if he can prove it. 
As has been said before, the plural of anecdote is not data.
Ah, yes, that bastion of scientific experimentation and research ‘it is well known’.
Around here, we like a cite. Have you got one?
As has been stated already there is $1,000,000 waiting for the first ever demonstration of any psychic power. Still unclaimed. Why do you think that is?
Presumably you believe in alien abduction, crop circles, the Loch Ness Monster, remote viewing and Breatharians, which are all ‘well-known because many people have had experience of them’. Or do you have doubts about any of the above?
snicker I might just have to steal this for my next sig line.
I once visited a “psychic” in San Francisco she was amazing she knew what I was thinking about, details about my life that she could not have known. I asked her why she didn’t use her powers to play the lottery or the stock market, she told me she couldn’t use her powers to gain large amounts of money or noteriety. She also mentioned that many prominent “psychics” are actually fakers and frauds.
It’s called “cold reading” and some people are quite good at it. It’s not psychic at all. A good cold reader starts out fishing for general information that applies to nearly anyone (“You’re going through a major change right now…”) and most people unconciously supply missing information. They’ll never come out with a highly specific statement like “You are a secuity guard for The 3rd National Bank of East Bumblefark and make $36,000 a year.” It’s always broad, until they fish info out of you, then they get a little less vague, but always nonspecific. The sucke…I mean client himself provides all the info the frau…I mean psychic needs.
I’ve always wanted to have a “psychic” attempt to cold read me. Being the sceptic that I am, I’m sure that I’d be able to make things quite difficult for them.
More data. I mean anecdotes;
I just got back from my favorite cafe, where I experimented on three people. Two older guys and an attractive twenty-or-so young woman. I watched each one in turn for a few minutes, and the results were pretty interesting. Each one, within just a couple minutes, started acting a little hinky then turned and looked right at me. I was well within the rear 180 deg. of each one, so they had to turn and look to see me.
I stopped playing and resumed reading Apt Pupil. 
Even if some “psychics” are really “cold readers,” it doesn’t mean they all are. The woman I met knew things that I absolutely did not tell her. I am open minded about this.