Recently I have noticed that during hard driving (accel/decel), I feel something hit me in the back. It comes from within the driver seat and is not anything smacking me hard, just a little bump. I never noticed this until recently and it only happens with a fast take off or hard brake movement. It happens around the area of my middle back. Thisonly happens with forward/backward movement, not sideways.

Any one else have this?

 

Is it your lumbar support? I noticed it more on my 2006 with cloth than my 2007 with leather.