Screwdriver

I also have never heard of this type of problem. Especially one that a Ford service department would say that there is no problem with.
There are very few components that make the brake system work. The pedal, master cylinder, brake lines, wheel cylinders, brake pads and rotors or drums.
The warping is generally caused by getting the rotors hot and then driving through water puddles. That will warp a rotor very quickly.
I'm not suggesting that is the case here but people that don't realize what they are doing and drive with their left foot on the brake most if not all of the time are actually applying some pressure to the braking system. this will get the brake hot, especially if it's is driven in heavy and stop and go traffic.
If this particular truck was purchased a used vehicle, it could very well be a preexisting problem.
I've driven nothing but Ford trucks and I recently traded a 2004 F150 that had an excellent brake system.

I would strongly suggest that you contact a Ford Motor Company representative personally and ask them to evaluate the problem.