Completely normal in an Audi. All the Audi Xenons I've driven vibrate a bit. I guess it has to do with the automatic leveling.Does anybody else notice that the headlight beam seems to shake alittle when driving on country lanes(Xenons). It very slight but never had it on any other car but then Ive never had Xenon lights before. Maybe its due to the fact that they are on the self levelling system.