Was I rude to my female friend (facebook message)?

[virgil]

I'm very busy right now with grad school classes and an internship. I almost never go out or hang out with friends because I don't have the time.

A female friend of mine messaged me on facebook and asked me if I want to hang out. We're friends and one time we made out but stopped there because she wanted to remain faithful to her bf. Which I respected.

Anycase, I messaged her back saying "Maybe. What's the % chance you'll sleep with me? We can hang out still, but I don't have a lot of time these days". She never messaged me back. I didn't think I was being rude but my sister says that was very rude of me (she's best friends with my sister as well).