The act of offering you some of his lip balm has no inherent indication of a flirting situation to it. However, what you have observed about his presence (body language and eyes etc.), are what may give you an answer. Suffice it say, it's a stretch if you think that in itself is flirting. To me, those actions indicate that he's being considerate.
My word of caution:
If this is wishful thinking on your part, you may want to save yourself some trouble and find a dating situation outside of your roommate. It can get quite sticky very quickly. Especially if you don't know him really well and you aren't exclusive - just for starters. When that kind of situation ends..or goes bad, it causes nightmares.