As your video feed and aircraft control were unaffected by this incident, I'm thinking it might have just been a gimbal problem rather than any jamming or interference. Was it windy that day?
I have had similar experience where in fairly windy conditions above a hill the picture (when the aircraft was orientated in a certain direction) would rotate alarmingly and jump about like it was having a fit. Still had full control of the bird but the video was all over the place. When I dropped down and flew away from the wind the picture still jumped around for a bit before setting down and stabilising.
At one point I even received a motor overload message - t was just the wind blowing the camera about, presumably eddying around the front of the Mavic.