My gf has been hanging out with her old friend, should I be concerned?

She said hes just a friend, even refers to him as her "homeboy." And I know shes been hanging out with him lately. But she tells me whenever she hangs out with him and what they do, so its not like shes hiding anything from me. I know also she has lots of guy friends more so then girlfriends because she says she gets along with guys better. She even invited me to hangout with all of them (her homeboy included). Should I be concerned? What should I do?