This happens every time the missus goes with me. All I've ever had to do was rub it down with some Turtle Wax Chrome Polish (a little elbow grease is needed, too) and it comes right off. A pair of passenger peg adapters would be real nice so I could put a different setup back there to keep her boots off the pipe.
call absolute cycles in Aberdeen, MD. They have this metal polish that removes rubber from chrome and it doesn't even require too much rubbing. Won't scratch the metal and can be used on all of the polished or chrome pieces. It's called Colonel ___________. Ask for Luke and he can help you.