I don't think that it's necessarily true that the girlfriend still has a problem with him hanging out with this old friend, even if she once did have an issue with it. Things change -- who knows how she feels about it now.
I think there is a fundamental problem with a romantic relationship that necessitates limiting your interactions with friends. That's a huge red flag right there.
But I also agree that if the boyfriend's priority is hanging out with his friends over making his girlfriend happy, that's also a problem.
I wouldn't want to be in either situation.