What would the girl think?

I think it's a sure sign you're a gentleman, at the very least. You don't say if you do like her, or if you want her to think so. If it were me, I'd get the impression you're a nice person, although it wouldn't necessarily make me jump the gun. If you do like her you should tell her, if it's just a casual thing to you, continue to be nice but don't give her any false leads.