Dude I don't think you should have given the bad waitress a good tip just because she was cute, some people think they can get away with whatever they want just because they're attractive, don't encourage them. Maybe I'm judging her a bit unfairly but that's how I would've seen it if I was in your shoes.

To answer your question sure I think it would be ok; you know your reasons for doing it aren't creepy and if you're still worried about what the hostess thinks you can always tell her that the waitress you ask for is better than ones you've had in the past.