????Little bump on boxers lip?

there's a little pink bump on my dogs lip, like on the upper jaw under the whiskers. i havn't noticed it before, but he has a lot of moles, so could it just be a mole with no hair over it like the others??? or a zit??? or something worse like cancer??? he has an appointment in a week to the vet, but i woudl just like to know of any possibilities in advance?? any help would be greatly appreciated