What does it mean when a guy days you're a good girl?

I'm seeing this guy and we met his basketball coach at the bar and his coach tells me that the guy I'm talking to is a "good guy" & then right away the boy I'm talking to goes "she's a good girl." Then later I told him that I am going to work on improving some qualities about myself that I know annoy him slightly and he says " if you change make sure its for yourself and you're a good girl, so you shouldn't worry about it haha." Guys...what's your opinion on this?