[masraum]

I suspect it has a lot to do with your attitude/how you come off and his attitude.

I'd think that with most adults in a casual environment, it should be fine. If you were to come off as condescending or racist, well, that would probably be bad. Also, if the guy has a chip on his shoulder or is sensitive, it may not matter what the circumstances are.

Normal adults probably realize that some folks use "bro" or "brother" like some people use "dude", "man", "guy", etc.... Now, if you'd said "boy", well, that would probably be really bad.

If you feel really weird about it, or you are worried about it. You could always mention it the next time you see them.