My puppies are black with white chest and white front paws. I feed them in metal bowls with a plastic rim and their water bowl is plastic . A couple times lately I've fed them on paper plates? I don't have any recent pics of them but I can have it up by tomorrow
What color are your pit bulls? White pit bulls can have shockingly red lips and mucus membranes inside the mouth, I have seen some who look as though they have eaten a fresh kill because their mouths were so red.
What kind of bowls do you feed them from? If you feed from plastic bowls they could have plastic bowl dermatitis. This can cause the mouths, inside and out, to become red and look very irritated. They can also develop small pimple-type rashes where they rub against the bowls while eating.
If you don't think that either one of these things is a possibility (I am only going by your very brief description, remember) then a call to your vet might be in order. Better to be safe than sorry. Do you have pics of your guys? We love puppy pics here!
Ghilly