Damnit, I HAVE to err on the side of accident, because I LOVE a sweet story like this
too damn much. lol...
I say you go back there and see what's up. Don't ask, just go start talking to him again. If he forgot your number, and really was interested in you, he'll flip out with happiness you came back, AND you'll have some currency to spend, seeing as he goofed and he owes you.
Otherwise, he might have a girlfriend, or just have forgotten. Besides, if he's in school at all, this is right in the middle of finals time. People forget who they are, let alone to call a girl, when they're in study/crunch mode. If you really like him, give him another shot.
Best of luck to you. Invite me to your wedding. lol