That's what he said earlier when she teased him about liking her. He never really corrects her or tells her she's wrong, he simply brushes it off. You're flattering yourself. Which maybe she is, maybe she is simply thinking she's more important to him than she really is but maybe she isn't.

He tolerates her more than just about anyone else. Sometimes she would even swear it seems like he seeks out her company -- even if maybe he's just looking for a good verbal sparring match. If he really didn't like her in some way he probably wouldn't listen to her at all. He's not the type to back down just because she's loud and stubborn. Her other friends sometimes just let her have her way because it's easier than fighting with her.

But not Vegeta.

She smirks a little in return.

"I'm not wrong, am I?"