Gremlins in the dash turned the key off while you were driving. Bug bomb the car, that makes them drunk, and then maybe they will only chew up the owner's manual (nobody uses it anyway).
Seriously, it's probably an isolated incident that will never happen again. Maybe the key was halfway between ON and ACC, and some bump or something caused it to back up to ACC and turn the engine off while you were driving. The thing is- the key was off, that's why the engine was off. Thank goodness you're in a DCT and not an earlier AT which wouldn't allow you to crank the engine while in D. That's something I noticed in reading your description. If it ever happens again, you can have the transmission looked at all you want to, but there won't be any problems there. The problem will be in the lock cylinder or the ignition switch.
---The Complete How-To Archive--
Moderating everything now, let me know if I can help.
Originally Posted by the user formerly known as ZX3_Chick
You're special aren't you.