It would depend if I wanted to go out with her. It used to happen to me pretty often though generally women are more indirect. They say they need someone to keep them company for some reason or something like that so they aren't just asking you out directly.
I'd be extremely flattered and grateful and probably thank her a million times, but I'm not sure if I would take her up on her offer straight away. I don't really go out with friends, let alone people I don't really know too well, let alone a girl D: