Yes, car has xenon's. So I called the dealer, a part was replaced last year, number 61-35-3-451-624. I cannot find a diagram where the part is on the car to confirm it's the same part, but it is described as "light module". If anyone can confirm or provide a link with a diagram, I would be appreciative.

In any event, all work performed by them has a 2 year warranty, so it should be covered. Even so, the problem description is the same, so if it's not the same part, I could still make an argument that it should be covered as a pre-existing condition prior to Warranty expiration. Car goes in next week.

Giving latitude to the dealer, I will assume that the part fixed the problem, but the plug otherwise became disconnected in the past year without my knowledge. The part has subsequently failed due to dirt and water entering the unit.
The dealer said they would take care of it.

This problem took the dealer a while to diagnose, so if nothing else, I hope that anyone else with similar issues finds this helpful. Proof that these cars are very integrated!