What does it mean when a guy stares at you, yet hardly ever talks to you?

There is this guy who all semester long has hardly spoken to me, but often he will stare at me, sometimes with a dreamy look on his face. Then, at the end of the semester he sits next to me in cl and puts his head on my shoulder pretending to be asleep. I think it's awkward A) because I am gay (I think he knows that) and he is known to be straight; B) he doesn't hardly talk to me so why is he so comfortable with me all of a sudden; and C) straight guys aren't that touchy feely. Is he gay, bi or just a really a sweet guy?