I have an interesting update for you guys. It turns out that the projector is the one that is moving, not the screen.
The projector itself is mounted on a 24-inch extension pole and while the roof has been deemed as rain damaged in parts, there is no visible damage near the ceiling mount.
Now, when the door opens and closes, the projector does shake (is this normal?), but the picture moves regardless of if the door has been opened/closed.
The distance that the image moves is about 3-4cm and it takes around 5-10 minutes for the image to move 1cm. If I turn the projector off and turn it back on 2 minutes later, the image will remain in its last seen position, and will then continue to move further up. If I leave it overnight, it will return to its lowest position and move its way up.
Should I ring Panasonic? Should I contact the installer? What should I do?