For anyone following/curious: I was able to get this to go away! Unfortunately I'm not sure exactly what fixed it, but I suspect it had something to do with the steering mode being stuck in some kind of weird state. I tried several things, including: driving with the paddles for a bit, toggling steering through all the modes, running in 4A for a while, toggling lane assist feature. Have driven several hours over past couple of days and no signs of the issue. Very strange but glad I can get back to enjoying the truck!