When I saw an RO print off with this description today, I thought the service writers were just coming up with their own descriptions again, but nope, this is straight from the horse's mouth...
#17249: Service Update - Chuggle Drive Quality - (Jul 17, 2017)
Chevrolet Silverado LD 2017 L83/MYC
GMC Sierra LD 2017 L83/MYC
Incidental engine combustion events, can occur at certain temperature, loading conditions and throttle positions. When limited or zero torque converter slip is commanded during these events a “chuggle” sensation may occur.
Reprogram the transmission control module.
Not sure what exactly a "chuggle sensation" is.