Be responsible and pull the drums and inspect. I would bet you'll find a grease on lining issue.
Also, just a suggestion to buy an inexpensive IR thermometer to carry in the tow vehicle and when you make stops, walk around and point it at the drums / hubs / tires on the tow vehicle and trailer.
We caught a dragging / stuck left front caliper on our truck once (and it wasn't pulling to the left either) and a incorrectly adjusted brake on the RV (on the way home from buying it).
$25 and a bit of diligence will save you a LOT of grief on day.
Tina + Dutch and Bell, Bobo, Harley, Buddy (the dogs)
2011 F350 Lariat 4x4 DRW SuperCrew 6.7L (B&W setup w/Air Lift 5000 Ultimate)
2014 Columbus 365RL (Airflex and Voyager package)
Nights Camped 2014 - 154
, 2015 - 32, 2016 - 4