I'm in a situation where there's a lady at a local hobby/interest thing, whom I really like- though I've not had the opportunity yet to talk to her a lot. I've not yet determined whether she'd be interested in reciprocation.
I would say, if you get an uncomfortable vibe off this guy, and you don't like what he's doing now, then let him know he should stop it.
If you think he's all right and not creepy, then there's the opportunity to talk to him a bit more and get to know him, if you are likewise interested (platonically or otherwise).
In your situation, I would be more likely to interpret his behaviour as somewhat stalkerish, but that's also because I'm not quick to trust most people to begin with. Swarming around me to spend time with me is usually a no-no.
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clarity of thought before rashness of action