This just screams creepy stalker guy. Then again, I knew a guy in HS that liked to follow girls to talk to them.....he also enjoyed when they tried to ditch him, the whole "thrill of the chase" thing....I thought he had issues. He certainly wasn't a stalker, but I'm sure he freaked out lots of girls.
I'd just stay away from this guy or maybe talk to him in a safe place. If I did talk to him, I'd confront him about the whole thing though and find out what's up....I'd have some trustable guy friends on hand.
b