Am I crazy for liking him?

So I was walking through town yesterday and this car pulls out of a fraternity driveway right as I'm about to walk across there. He immediately stops, smiles, and says "Sorry" (his windows are rolled down). I just simply smile back and say "It's okay" and we continue on. Ever since then I can't stop thinking about him. I really want to see him again. But I don't even know him. I've literally been thinking about him 24/7. Is this creepy/crazy? How can I like him if I don't know him?