I have had my car for less than 300 miles and I have noticed it happen at least twice.
I think it happens when your car thinks you are about to downshift and are in sport plus mode.
I got ebony premier trim and stitching is grey/silver. I can upload pictures later today.
Also the leather is much softer than the non premier and also ads soft touch upper door panels
I got 401A package and dont regret it one bit. 12 speaker with sub, blind spot assist, memory seats with easy entry/exit, and hd radio all for $1600 if you have xplan. I think the sound system is great and I dont know why people think it sucks.