I had 50 pre-upgrade flights without any issues.  Then my iOS version upgraded just before I went on vacation so I also updated the firmware.  I took a few test flights before leaving and everything seemed fine.  In fact, I took the P3 up on 3 20-min flights on the same day it started acting up.  But on the below shown flight below, I took it up to catch us jumping off the top of the boat and it sorta just started to 'twitch'.  It fell about 5-10' on two occasions before I brought it in for the day.  Scary considering it was only about 20' up, and over the ocean, when it happened.

https://www.youtube.com/watch?v=Hlo_MTlyOcY&spfreload=10

A couple days later, I took it out again to follow a pod of dolphins and about 12 mins into that flight, I noticed that it would suddenly jerk the yaw extraordinarily fast to the side.  In the below video, I never yawed to the right (3 times in a row, it did it on its own).

https://www.youtube.com/watch?v=G4JSeikpjxY

Lastly, I've also noticed that only recently, when I tilt left or right, the gimbal doesn't always react and catch up.  Sometimes the view is perfectly level and nothing is wrong but other times it tilts with the bird and looks silly on video.  Never had either of these issues pre-firmware upgrade (although I'm not really blaming the upgrade, just the timing of it).

https://www.youtube.com/watch?v=SumL4j3yJAA

Can anyone make heads or tails of any of this?  I'm sorry for the quality on these videos ... they were taken from the DJI app and not the SD card.

(Edit:  How do I change the YouTube links into actual video thumbnails?)

The last video looks like you accidentally pressed the C2 button on the bottom of the controller and set it to FPV mode ( instead of follow ).

For the other issues, I have no idea. There have been mentions of one of the little screws on the gimbal being loose that caused similar issues, maybe have a peek at that.. Beyond this, I would contact DJI and supply them the video and logs.