Hmm... last time I was at the dealer and explained my symptoms (including that of a little side-to-side play on the highway) the SA stated that the symptoms sound like those of a faulty rack... (leading me to believe its pretty common).
I asked them to inspect it and he said they would - and after I got the loaner and drove it I sent the SA an email asking him to make sure to include it on the work-order so they could check it because the loaner E90 steering felt unbelievably better... However when I picked up the car there was nothing about inspecting the steering system on the work-order and when I asked the SA about it he said "oh they said everything is fine"...
More and more I've been noticing that when the car has not been used for several hours, for the first few minutes of driving I can feel a strong shaking while turning the wheel (even if turning it back and forth just a matter of 2 inches to each side) - the shaking has nothing to do with the road surface of the vehicle speed - it almost feels like the insides of the tires were off-roading tires... And turning the wheel each way has un-even resistance (notchy feel). It leads me to believe that there is something wrong with the hydraulics of the steering system and it acts up more when the power steering fluid is cold.