Nope, I'd have no problem at all and would be delighted! Your professor may ask if there is anything he or she could help you with, but that's just because most students want something from us. I had an old student drop by just the other day to chat, and that was great! Don't fret too much about your email. Maybe just say that you don't need anything, but that you enjoyed her as a professor and an individual, and was there a good time you could drop by to say hi and chat before you leave campus? Congrats on graduating!