It could be along the same lines as a girl calling a guy she is not romantically attracted to "hun" or "sweetie?" That's one guess. But does he only call you "dear?" Or does he call more than one girl "dear?"
For some guys, it's a "petname" and others its just their personality. I have a guy at work who calls all the girls "dear" or "honey" and that's just the way he is. It'd be different if he was just calling me dear, then I'd have to set some boundaries he obviously don't know exist. But if he's calling just YOU dear, then maybe he does like you.
Depends on the guy. If he calls other women by "dear" or something besides their name, then probably no, but if you're the only one, then it could possibly be something more. But then, he might have just forgotten your name! I'd look into it though.