I'd keep the fish in QT and keep an eye on it. It could have gotten nicked when being caught, packed and shipped. I have a potters angel that gets bumps and scratches from time to time, but they heal quickly. If you feel it might be ick, you may want to do a freshwater dip, or hypo. Only problem is that a new fish is stressed enough as it is from being shipped, that if you stress it out too much, it may refuse to eat and die miserably.