Less than 30 miles and two hubs cool, one warm and fourth quite hot. Jacked each wheel and spun tires proving two right sides were dragging shoes on the drums. Left sides were OK.
Dealer recommended wheel and axle shop much closer to me than 16 mile freeway drag. Cool morning and on arrival, found both right sides hot after only 6 miles. Past experience with the shop resulted in jacking rig and found all four dragging. Decision made to remove the self adjusting hardware and replace adjustment wheel mech. with standard ones. Did not change back plates or shoes etc., simply removed the offending crud.
It is possible these wheels got wet as there was a heavy rain causing flooding of the dealer lot after the trailer came in. I observed rust on springs etc. that seemed a little early for 2016 brakes.
They were not installed backwards either as shop checked for that and mentioned it. I paid $200 for parts and labor and will now be able to adjust all four wheels while on the side of the road if needed. Shop told me the self adjusters did not allow easy backing off on the brakes as they were designed to only go one way.