I just posted on this a few minutes ago elsewhere. I have not had any problems with the shifter either.

Page 60 of the owners manual states that PARK is auto engaged as soon as you shut off the engine unless you are in N or the Comfort Access remote is in the ignition.

I will hae to test the time out and opening the door without being seat belted.

__________________
2007 4.8i, Space Gray, Dark Burl Walnut Wood, Black Nevada Leather

Packages:
ZCW Cold Weather, ZPP Premium, ZRC Rear Climate, ZSP Sport, ZTP Technology

Options:
217 Active Steering, 322 Comfort Access, 328 Running Boards, 496 Heated Rear Seats, 610 Heads Up Display, 655 Sat Radio, 840 Increased Top Speed to 150 MPH ,2LE 20" Y Spoke Wheels.

Mods:
Stainless Steel Pedal Pads