AITA for telling my girlfriend not to call my dad “doctor”?

My girlfriend recently got her doctorate. I’m obviously very happy for her and proud of her.

Since then, she has been greeting my father as “Doctor” [lastname]. Although he does have a doctorate degree, no one has ever called him that, and he told me it makes him uncomfortable.

I asked her to not call him that. She says that she wants to be polite and call him by his title. She now wants to be called doctor when might parents greet her as well.

I understand it’s a massive accomplishment but I don’t think she should expect my parents to call her doctor? And she should not call my dad doctor if he asks her not to.

She thinks I’m trying to downplay what she did but I’m not.

AITA?