Make sure PrimeTime is fully aware of the water damage issue, and that they have logged the issue with your unit. That is the date relevant to warranty. The water has to be coming from somewhere!
The fact that your dealer cannot find a leak doesn't mean you don't have a problem! It just means that the dealer can't find the leak.
You do use a pressure regulator, right? Is there any possibility that water came in at some time through or around your roof vent while the rig was not in use and dried up before you could notice it?
This is a mystery...
Jim & Kathy
2012 Crusader 290RLT TE, TrailAir flex pin: 2012 Toyota Tundra 5.7 SR5 Dbl cab 4X2 Tow, 4.30 gears, RideRite air, TRD cold-air induction & dual exhaust: Reese 16K Slider: TST tpms
Miles towed to date: 18,950 Nights camped 192