My first thought would be a little Goo-Gone, but you have to be careful not to leave it on too long, and thoroughly wash it off after application, as it can damage the surface finish....
I think a guy I used to work with used WD40 to remove stickers from the floor without damaging the wax.
Trumpet oil. I cleaned so much sticker goo from guitars when I worked in a shop. Trumpet oil was the ticket. Let it soak in for a few minutes and it would take it right off.
Trumpet oil? Sounds like a recommendation from a guy blowing his own horn....:earl: