What would you do if your boyfriend said this?

I was thinking about something my ex said to me after I broke up with him and I was wondering what you would think of if from the perspective of the new girlfriend if you found out your boyfriend said this to his ex “Even if I have a new girlfriend and you want me please back tell me” would you be worried if you heard he said that? I just wanted to know cuz I never thought about that until I remembered. (BTW I don’t want this guy back I have a new better man lol I’m just asking cuz why not.)