So I take it you are having transmission and shifting issues??

I would check the fluid, maybe drop the pan and check/change the filters and replace the transmission pressure switch

 

It was weird, I started the truck, put it in drive and pulled forward about 8 feet and then stopped. At that point it felt like someone rear ended me - the truck jumped forward. It was a minute or so and I noticed the light on. The truck drives fine and I got the codes from autozone. I have never messed with a tranny and I do have a drivetrain warranty. And there is only 49500 miles on it.

 

Any update? I'm having a similar issue except mine siims to be intermittent. Got stuck in 3rd gear (or what I've read to be called "limp mode") one day and the next the check engine light was off and it shifted fine. Sometimes it's ok sometimes it's not.

Just wondered if you tracked your issue down yet.

 

This may be anecdotal, but I would just change the tranny fluid to a high quality brand, make sure you are 100% stopped before changing from R to D, and always use the parking break from now on. With any luck, you may not need to repair anything.