It happened to me on the kitchen slide out, near the refrigerator. The slide out floor was rubbing the main floor while retracted and traveling.
The slide out floor and wall looked normal when extended, but the floor wall separation was visible when retracted.
Chris and Pat
2016 Ram 3500 Cummins Aisin Dually, 4.10 axle, Auto Flex Air Ride Rear Suspension, Pace Edwards JackRabbit tonno, Transfer Flow aux fuel tank, B&W RVK3600 hitch
2017 Cedar Creek 36CKTS, MORryde IS, Disc Brakes, 17.5"