Cruise Control problems of the 2014 Chevrolet Silverado

I pulled out of a parking lot on to a city street and pressed the gas pedal a little, planning to get up to about 25 mph because there was a red light a block away. The truck responded as if I had floored the pedal. I took my foot off of the pedal and the truck kept accelerating at full throttle. I hit the brakes thinking the cruise control had gone nuts, but hitting the brakes would not turn it off. It kept accelerating with the tach over 5000. I shifted to neutral and the engine speed dropped down to idle. The light turned green and I shifted back to drive and the engine immediately started accelerating again at full throttle. I put it back in neutral, moved over to the shoulder and turned the key off. Then I started the engine again and the problem disappeared. I'm 72; if my wife had been driving by herself, she probably would have had a serious wreck. The truck is a 2014 Silverado, bought 4 weeks ago, 6 cylinder work truck.