I recently had a 1997 Jayco that was in excellent condition. It had been stored in a pole barn and used a couple times a year. It started leaking out of the center light fixture so I inspected every inch of the roof and everything looked fine. It ended up being the rubber boot around the antenna cable.
It looked ok but had relaxed enough over the years that it would let enough water by to cause a slow drip. The water would run across the top of the ceiling panel to the light fixture. So.....your leak may not be directly above the window area.