Not with the 987S, but I used to have an oversensitive alarm in my Audi TT. The motion sensor was going off too easily, e.g. when I was parked in a multistory parking facility and a couple of large pickups or SUVs would drive up the ramp my car was parked at. The ground vibrations made the alarm think the car was being lifted. I brought it in for service and the dealer was able to adjust the sensor so it wouldn't go off on a whim.
To cut a long story short - Are you by chance parking on a bridge?

Can always have the OPC look at it and see if it's by chance too sensitive in setting.