Transmission Question

I have a 2003 silverado V6 automatic with 13k miles. This truck has been great until today. After driving for 30 minutes I turned the corner to my street and then heard the engine rev up. I looked down and the shifter still said it was in Drive but it was like it shifted into neutral. I rolled for about thirty feet and tranmission seemed to go back into drive by itself. Has anyone had this happen to them. Fuid level is fine. And I am going to bring it back to the dealer. Thanks
:confused:

I have been experiencing something similar with my 03 4.8L I just took it in to the shop and they said there was a computer update to help with hard shifting between 1st and 2nd gear. While this definitely makes it feel smoother, I experienced the "slipping" again today when accelerating from a stop light. It feels like it goes into neutral and then pops back into gear.

( I have a 6" suspension lift on there with 33" tires so they are telling me that anything with the drive train will be voided on the warranty)

Any ideas or fixes???