I have something similar with my
P4P, a slight panning turn that can only be seen by looking at the image edges. It's just enough to limit exposures to no longer than about 1/10 before blurring is an issue. However, I noticed that it mostly stops after maybe 5 to 10 seconds of hovering in position so at least I can live with it provided I'm not in a hurry on my long exposure panos.
As KingDad says, I think it's an issue with the camera pan lagging after azimuth turns, I can see something like that if I manually turn the aircraft while it's sitting on a table. Hasn't changed since the most recent firmware update.
I carefully balanced my props and found one that was pretty far off but that didn't change the turning issue. I swapped the bad prop out for a new one in better balance, then trimmed it slightly with nailpolish.