Well, I think if your have eliminated the obvious ones (seasoning and condensation) than you probably have a leak.
The first thing I would check is the seam with a flashlight and then probably go into the dealers to have it taken care of under warranty.
This will take a couple of people, but at night when its very dark, have someone shine a flashlight at the zipper and seams from the outside. You will be inside the camper and will check for pinholes, tears, and gaps. There may be a defect that you can see to point out to the dealer.
Definitely take it back to the dealer to have them repair.
DW, 3 Kids and our Goldens
2012 Shamrock 233S
2008 Toyota Sequoia 5.7L 4WD