My girlfriend calls my best friend by her boyfriend name

I am in my head about this issue and I want to know what do you think about it. My best friend is named Ed, and he’s never seen my girlfriend. He lives out of the city, and actually I didn’t see him in months. My girlfriend always calls him Ted, never Ed. I don’t argue with her and I actually like Ted, but it feels weird that she always calls him Ted. I’m not sure if she even knows if that’s his nickname or not. I don’t want to make a big issue out of this, but I feel that I should speak about it.