Here's a weird expression of this rotate bug. With the bug happening, I took two photos, one landscape, one portrait orientation. BOTH were rotated 90 degrees from what they should be! Landscape photo 90 degrees clockwise, portrait is 90 degrees counter clockwise. I expected one of them would be correct.
After reboot, new photos are OK.
Also confirmed with Swiss Army Knife bubble level that the sensors are wonky - jumping all over the place when I tried to calibrate. Reboot and recalibrate and all is OK.
FWIW, I never connect to computer by USB. I think that virtually all the commentary here about "it must be this" are red herrings. We seem to agree that reboot can fix it and good observations so far indicate that a OTA update brought this problem to us.