2009 gmc downshifting problem

My 2009 gmc sierra work truck has a 4.3 engine, but it seems to downshift even on a very slight grade uphill. Is this normal? I understand that it is only a 4.3 engine, but it only has 50000 miles on it. I have the 100000 mile powertrain warranty. Is this something that needs to be taken in for service? To downshift constantly does not seem normal. Any advice would be great.--------------1/2 ton pickup

Looking in my general resources for the 2009 Sierra I was unable to find anything to point you one way or another in regards to the shifting concern you've described. If you do decide to visit your dealership, please keep us updated as to your progress there. I am available to assist in that process if you like, as well. Send me a private message with the last 8 of your VIN as well as the name of your dealership.

Kind regards,
Sarah
GM Customer Service