Should I be calling Africans "brotha"?

I was in a Taxi today with this somali driver..As I gave him a tip he say thanks "brotha" in broken english. I usually never talk to these taxicab africans cause I can never understand them anyway, but this somali caught me off guard.I froze and didnt know what to do, I only say "brotha" and "sista" to American blacks...It just sounded weird coming from an African..