Auto trans shift problem on 2012 SC

I need to ask you TW members if the intermittent shift problem I'm experiencing is just me: I drive a 2012 SC 4x with 265's about 70 miles a day. In the last year, while taking off from a light, the truck tried to take off in high gear (shifter in D3 with the shifter pushed to the right). On both occasions, I momentarily though my truck had stalled, but during the most recent event, after I stabbed the throttle hard, I felt the transmission drop through the gears into first. Today, and on many occasions, when accelerating from a metered on-ramp (or the like), while driving at about 30 MPH, the trans would not downshift into lower gears. After reaching 50-60 MPH it downshifted when the throttle pedal was buried in the carpet. No check engine light during any event, and the dealer could not replicate the problem. I got a "Holy ****" from my service advisor after explaining the issue, leading me to believe this must be rare. Does anyone have this problem?? I'm an old school hot rodder who'd start looking for a sticky valve body piston, but believing the trans is ECU shifted, it's hard to tell mechanical from electrical. I'm guessing that a programming fault would not record a code, but a mechanical malfunction would??