What kind of cereal? I have the same problem with oatmeal and cereals like
cheerios,
honey nut cheerios, fruity pebbles, lucky charms. I am fine with honey combs and chocolate rice crispies. (rice crispies are gluten free) I think it has something to do with some sugars and or certain fibers in them. I don't have celiacs or a gluten disorder that I know of eaither.