I would be inclined to take the back mattresses out, close up the bunk ends and have you or someone else give the exterior a hose down and see if you find a leak.
I agree with others that it sounds like canvas was not properly tucked in from the seal.
Also, when the canvas is stretched water does not pool on the canvas. It runs off properly.
If you have pooled up water on a canvas material, it will leak through, eventually. The literature that came with the trailer does not state the canvas is waterproof!
I would say if the problem was your fault, tuck your tail and run!
If there is a seal failure, which could be pinpointed by hosing down the trailer and having someone inside watching for water intrusion, then you can seek to have the dealer replace the seals and possibly the mattresses.
2008 Toyota Tundra Crewmax Limited w/tow mirrors, 5.7L, 4.30 gears, six speed tranny, towing package, Firestone Ride Rite airbags.
2014 Rockwood Roo 233s, PI HW30-C, Equalizer 10k 4 way hitch,