I think you might be on to something.
On this PRU, the place where the head gets parked after a print is normally about half an inch to the right of the stop. I also think that’s the natural home position for it.
The only time I’ve had the whacky-whacky happen is when I have accidentally moved the head all the way to the left against the stop. I think it’s just expecting to start about half an inch further over to the right. (I move it during cleaning, or if I have to stop a print for any reason.)
The whacky-whacky will continue though until the whole shebang gets reset by turning off the machine, centering the head under the lid camera, and letting it reset itself once. After that, I can turn off the machine normally, and it starts itself back up properly over on the left side of the bed.
Like I said, I don’t see it often, but I also don’t move the head by hand, even with the machine turned off. If I just don’t mess with it, it’s not usually a problem for me.