Drove my 2013 with HID's at nighttime for the first time today and instantly noticed the headlights flickering over bumps; even on the small road imperfections.
I never had this happen (HID's flicker/jitter) with my BMW e92 335 or either of my Audi S4's.
It appears to be either the bulb or housing is loose.
With this apparently a somewhat common observation, I'm guessing a headlight or headlight mount design issue could be the case as well.
I'll look to make sure the housing and bulb are seated correctly and go from there.
Any other suggestions besides replacing the headlights to aftermarket?