Definitely sounds like he likes you and is trying to find reasons to talk to you and be around you.
Maybe he is looking for a sign you're interested in order to ask you out and your "cautiousness" is confusing him, especially if he's seen you flirt with other guys. If he's in a field that you don't interact with much, it's not likely to cause problems at work if it doesn't work out. Let him know you're interested already. Or, just ask him out.