i have a tower hobbies kaos .40 that did that. but it was not used but new. the covering on the top of the wing came loose on the 2nd flight.. i got it down in one piece. i re- treated the wing with a light coat of balsarite and ironed it back down. that is one of my biggest gripes about arfs is the the covering jobs from the factory are poor. the coverings are heat oven shrinked on and the glue does not adhere to the wood.