I have had my car for 21 months now and I keep having a problem with the middle row seats releasing and popping up on its own. The back of the seat remains intact while the cushion pops up and acts like a catapult. This has occured while my 4 year old has been in his car seat as well as overnight while the car is sitting in the driveway. This is such a safety hazard and GMC has officially told me that they are not going to do anything about this problem because they can't figure it out. I even purchased a new booster seat thinking that was causing it and it still happens. Any one else out there having a similiar issue?