Noticed this behavior, the back light for the display stays on with no image. Have not left it that way yet to see how long, the way to kill it is unlock again, open door, close, and lock.
Anyone else notice this, or do I have a bonus feature?
Why don't you leave it and see how long it stays on. I would guess it will turn off after 5-10 minutes tops. It might be booting up in the background so that it's ready to go when you get in the car. If you don't open the door though, it should shut back down after a bit.
I honestly don't know, but maybe if you hang around the car with the fob in your pocket, the car senses the fob and stays ready for ya. Try putting the fob far away from the car (or in an rfid pouch) and see what happens?
Considering Sync 3 is designed to download updates when you are parked at home, my guess would be that its just checking for updates. Like others have said, leave it and see if it goes away on its own.