These photos will give you an idea of how the frames arrive at Keystone, how the tire/wheels arrive at Keystone and how the axles arrive at Keystone. As Danny posted, the workers on the assembly line push an inverted frame into position 1, install tanks and coroplast, put axles and stabilizers on it, turn it over so it's "right side up" and install tires on the axles. Then they push the trailer to position 2 where the floor is laid on the frame and the trailer goes to position 3 and then on down the line.
What happened with your trailer is anybody's guess. Contact your dealer and let them know what you found. I'd guess that if your trailer is supposed to have self adjusting brakes, they'll report the problem to Keystone who will authorize a parts changeout. If it's supposed to have non-adjusting brakes, they may make some other decision.
Let your dealer know and see how he handles it. Calling or emailing Keystone demanding action will only give you a "Pepcid moment" or a "Pepcid month"... The dealer has to initiate the warranty claim, so trying to short cut the system will only cause you more grief than it's worth.
OOPS: Forgot the photos, Here they are
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS