What does it mean when a girl mentions a girl as an "old friend"?

Ive been talking to this guy for a while...and i called him earlier today and he didnt answer my call. and then he texted me and said "Ima call u a lil later ...im talkin to one of my old "girl" friends not ex a girl thats an old friend lol". And he has a lot of groupies. But i don't know what to think about that. Why couldn't he just say friend ? why did he have to specify it like it was a big deal and sound all sketchy ? Am i overreacting ?