2014 Silverado Grade Breaking Question

[Striper]

Hi, I have a 2014 Silverado extended cab pick up with 60,000 miles. In July, for the first time while driving on a completely level interstate, the grade braking function engaged. I was not towing a boat, trailer, nothing. I stopped the vehicle, turned the engine off and proceeded without it coming on again. Then, shortly thereafter, it started coming on regularly on completely level highway. I have been deactivating it by holding the tow haul button down for six seconds. I have had it to the dealer twice to run through the computer, but it continues to come on. I did not have this problem for the first two years of driving this vehicle and I purchased it new. Has anyone else experienced this? Can anyone else offer any explanations or suggestions? Thanks

[pickmeup]

Believe grade braking is active every time you start the vehicle. If you do not want it active you have to push and hold tow button 6 seconds or say and it will tell you it is off on message screen .