I couldn't say what it is but I think you should talk to him. Unless you wont be seeing him again? I don't know about the situation but it's always fun to strike up conversations with people on the street. Even if it's about the weather or the atrocious service at a store or something general. Go out and take a chance

. Maybe he's felt the same?
A friend of mine liked a (really hot) guy on the bus and we eventually convinced her to start up a conversation and now she's best mates with the guy and his (hot twin) brother.
And a teacher I used to have said she met a man who she totally hit it off with. I don't really remember the details but I do recall her saying that the first time they accidently bumped hands she felt like she got an electric shock and she then started avoiding him. Now, though, she flies to scotland during the holidays to visit him.
So, give it a try, what is there to lose?