Is it common for a FWB to (jokingly?) call you his girlfriend?

Today in class we were kind of cuddling/hugging and one of his friends goes “stop flirting you two” and he replies “why not, she’s my girlfriend.”

I didn’t know what to reply so I jokingly said “yeah definitely” and that was the end of that. We didn’t talk or hug anymore (it was the end of class) but we didn’t speak again. Maybe there was tension in the air?

Did he mean anything by it as in he wanted to date instead of being FWB or was it probably all a joke?

He has joked about me having a crush on him before etc however I think thats just his style and he could say the same thing to other girls.

He has a lot of other girl friends that he jokingly pushes etc however I haven’t seen him sit there hugging other girls like he does to me. He’s sort of a playboy ngl.