Here is the deal. After braking (soft or hard) when I release the brake pedal then accelerate, you can hear the brake booster diaphragm "pop" back to neutral. After releasing the brake, the brake pedal returns instantly to the standby (non-depressed position) but the booster goes on a few seconds later to sound like a damper door shutting. I took it in and the techs (along with help from the engineer help line) diagnosed it as a harmless sound that is a by-product of the design. They said they tested another '09 on the lot (new) and it did the same thing. If it did it everytime, I might buy it, but it is intermittent. Anyone else out there had something similar? I am at a dead end (at least with this dealership)