E55 Estate Fan

Last night, at c.1.30am, I was awoken for a second night, by just the hazard lights on my E55 flashing at double the normal frequency (I'm a very light sleeper!) The horn did not sound. There was nothing wrong with the car i.e. no attempted theft, all windows/doors/tailgate/bonnet were closed firmly. The car is parked on a gravel drive, I am often awoken by a cat or fox walking across it, so am confident nobody tried to tamper with car, as I heard nothing.

Q.1 Assuming it might be the interior motion sensor (IMS), is it normal for the IMS to be triggered by say a fly or spider inside i.e. is it that sensitive?

Q.2 If it was the IMS being triggered, is it normal for just the hazard lights only to be activated i.e. should not the horn sound too?

Q.3 If when I try deactivating the the IMS it happens again, could it be a bad earth to the lighting circuit?

Q.4 Should I get the OEM alarm system looked at by MB? Or is this normal?!

Here's hoping for a good night's sleep tonight

Chris

E55 Estate Fan

Update: In daylight today have found & removed, an almost invisible spider's web right in front of one of those sensors

So to all you with these sensors, get busy with your feather dusters