I would have the outer axle bearings checked. It may be binding a bit when torqued to one side or the other but still holding it's own (less straight forward stress) when moving straight forward. Next time it happens, if possible, find a safe place to pull over an feel the temperature of the wheels...see if that side is warmer than the wheels on the other side. Not to sound scary, but if this is the case, it could lead to something really dangerous if they totally locked up.
2018 THOR Chateau 35SF
Two Labs, Bugsie & Blondie