My BMW daily drive has Xenons and they adjust if the suspension has unequal loads / extension front to rear - so when there is a load in the car and the rear springs are compressed it adjusts the lights down.

It will also adjust when manouvering on uneven ground when there is a twisting action on the suspension and one rear (or possibly front) strut is extended more than the other.

Maybe why Stuart's car adjust the lights going into the garage if there is a cross slope?