Dont panic. Its just a little irritated. Ive noticed the same thing on mine from time to time. Just give them a multi and perhaps an iodine tab and give it a couple of days. Its like us when we get a bruise or blister. Examine your tank and be certain there is nothing that could irritate them. Other than that, Im sure it will be gone in a couple of days. They are especially venerable to it as juvi's because the are more skin-like than scaly.