kdbcom,
Yes, it would seem logical that the onboard computer adjusts some settings when xenons are present. I have normal lights and when I enter a tunnel they pop on and when exiting the tunnel they go out again. A loaner (c-Estate) I had with Xenons had the same only with longer intervals. Once the lights were on they were kept on for about 2 minutes.
In the Netherlands only cars built after 1-2007 are required to have levelers and washers when fitting aftermarket Xenons. But there is almost no check if that's really the case. My car is built end 2006 so I am not required to have them.
But Pilot offers aftermarket height leveling:
Automatic height leveling*-*www.pilotxenon.nl and washers
Automatische hoogte regeling*-*www.pilotxenon.nl (bottom of page).
But it does all add up to a nice price. But I bet it's still cheaper then factory fitted !