Alarm Going Off Randomly

[mgfranz]

So this is weird, I can let my '01 986 sit for a day or two with no issues, put a few miles on it, bring it home and park it and everything is fine. Go back out after a day and drive it for a few miles, park it, lock the car, and the alarm will just go off after 10 minutes.
I deactivate it with my FOB, check the vehicle and relock it. I can be standing near the car and the alarm will just go off by itself. What would cause the alarm to just go off? Could sensors be going bad? I know we can't disable them due to the immobilizer, and they can't be tested that I know of...