If your trek bike has disc brakes, we need to see it. The front QUICK RELEASE may have to be replaced! We need your WHOLE bicycle. We need to take a photo of your serial number and send it to TREK for warranty purposes. No your wheel isn’t going to fall off,in most cases the skewer works fine. It just opens up to far. so if it opened up while you were riding it could contact the brake rotor! Thank you. If you have further questions contact us at 262-784-3151 or call TREK at 1-800-373-4594. The photo should help you identify if you have disc brakes.