We just got done with a two week trip out in Colorado and Utah and did some fairly vigorous wheeling (Gold Bar in Moab, Elephant Hill, probably the hardest stuff). Absolutely no problems up to this point, but on the way back to MO at interstate highways, I would occasionally get a back and forth cyclical swaying. Not very violent, not trying to spiral out of control, and usually sort of set of by a road heave or something. At first I thought perhaps it was 'pilot induced', but I'd stick my knee against the wheel to make sure I wasn't moving it, and it would continue. I found that making a larger swerve would sort of shake it out of its thing. And then it would go smoothly for a long while.
There's a sort of looseness around center in the handling, once you've turned a slight bit (like into a corner), the car 'settles in' and feels rock-solid, it's just a bit vague straight ahead.
I just haven't had time to crawl around underneath and look for issues. At a few gas stops along the way back we'd shake the car back and forth vigorously, and never saw anything serious looking (looking at upper, lower A-arms/ball joints, rear suspension arms, sway links).
The plan is to just go over it more carefully with a pry bar looking for loose/soft bushings, and if nothing shows up, take it to a shop and have it aligned.