I know this may sound crazy...but i have a 1999 F-150 ext-cab,5-speed, 6 cylander truck. it has almost 5000 miles on it. I have noticed a dent in the top rail of the bed, right below the rear window. I did not haul anything to cause the dent...it just appeared. there are no scratches or dents on the sides, rear bumpers of the truck. has anyone heard of the bed bowing any type of way that would cause such a bend in the top rail of the bed?