it happened this morning on my way to work
I turn up the on-ramp of the motorway, in the turn I feel some thump at the rear and she wobbles her ass a bit... I immediately hear the feared chime...

and the following message appears:
I continued driving, no loss of power or whatever...
when I was able to pull over, I turned the engine off, removed the key and waited for a couple of minutes, started again and drove off without error message
the car has only some 5000kms on it so this is under warranty but all I'll get is probably the 'could not reproduce' comment from the dealer as the message disappeared after shutting down the car...
Any ideas what could have caused this?