I don't know why I like him...?!?

I grinded with a guy at a school dance. We're seniors in high school, and I don't usually grind, but it's what 80% of people are doing for the whole dance. It was only for one song, and he did it with a bunch of other girls too and I didn't really care at the time.

It's been 4 days and I can't stop thinking about him. We're kinda friends, but I never liked him before.I don't know why I like him...I blame biology I guess. Men are programmed to run from girl to girl and women are programmed to get emotionally attached. I keep telling myself to stop liking him but I don't think I will for a while...

So what do I do? Should I tell him that I like him? Ask him out in a couple of weeks or something? The problem is that he has a lot of other girls who like him, and I used to think he was annoying, but I don't know...I feel something now.