If the glue is unnoticeable and does not bleed through like Activision's VCS labels used to, you are probably good to go. I highly doubt that it will ruin the value of the cart. Maybe in 100 years or so when these carts are dying antiques and SMB/DuckHunt is a 9 on the rarity scale this may matter, but like I said, if it is unnoticeable, and even experts like on Antiques roadshow can't tell, I don't see a problem. Perhaps you may even be increasing the value by readhering the label?

-Rob