I don't think it's glue. I think it is a dye from the label.
Maybe Rit color remover.

Goo-gone. (It feels like baby oil, but smells like lemon)

Just got something in my email that said "10 uses for Vodka" and one of those uses was for removing stickers. I've never tried it, but if nothing else works, might be worth it.

rubbing alcohol should do the trick.
Or like above Vodka I use it for alot of things.