I've just been to check the rear door seals on mine and found about 4 inches had come loose! All I can think of if there has been water in there, which has frozen in the recent chilly weather and pushed the pins out.
In your second picture you can see the small clips in the seal, these appear to be "captive" inside the folds of the seal. In addition to these clips, there should be a larger plastic clip at the top end of the seal, one at the bottom of the door where the seal turns to go horizontal, and then another one about halfway along the bottom.
My seal just clipped back into place, so I assume yours will do exactly the same
Check you still have the larger plastic clips in place - from your pictures though I'd say they are still there.