Its not normal in a pure breed boston terrier. Its normally taken as a defect in the breed. The AKC determines this feature a defect if your looking to register or breed your dog but other than that it is not something to rush to the vet over.....if you were given this dog under the impression that it is full breed healthy boston with champion bloodlines or whatever the story is than they were lying. A healthy Boston terrier should never have its tongue out unless he is panting for a bit or using it to drink water or lick.....BOSTON OWNER FOR 5yrs...