So on my last flight I noticed something weird going on with my gimbal, where when I would turn the gimble would tilt the camera at an angle and slowly fall into the correct horizon line. This was a little weird so I brought it down and recalibrated the gimbal and set it back to default settings and still had the same result.
Decided to take some video today to showcase what was going on so I started by IMU calibrating, compass calibrating, and gimbal calibrating, but the gimbal calibration got hung at 73%. Reset the drone and the app and tried again, where it hung for a shorter time at 73% then failed.

Here is the video from the flight today, doing the same thing from the flight a few days ago:

https://vimeo.com/203726811

Any idea whats going on here, or is there anything I can do to try and fix it?

I think that is normal, there is a gimbal delay setting somewhere...

Wowww... This is bad and NO it is NOT normal.

When you start the AC did you keep an eye on the Gimball initiation? Did you notice anything unusual like limping or not centering? Check the Gimball Roll in Gimbal adavenced setting see how far off is from zero.

Also when on the screen you should see the horizontal linein the middle of the screen, is it straight or off center on either side.

I think you need to adjust your gimbal to be horizontal. There is a setting for that. Just looking at the end of the video, unless your landing table is crooked, the gimbal is not horizontal.

Wow,

That definitely is not Normal. Would be more pronounced if you were in an open area and could see the horizon. Check out mavicpilots.com under "Mavic Pro a Help". There are several posts documenting this issue.

One other thing you could look at is to check and make sure you don't have it in FPV mode. That can also change the angle.