Allison trans issue

Hello All,

I have a 2003 LB7, on Monday I was driving on the highway at about 72 MPH with the cruise on. Fairly flat area and it felt like the truck downshifted. I looked over at my CTS3 and the rpm's were up a couple of hundred and the gear selection was only showing being in 5th gear. Normally it shows 5 TCL. After a couple of miles the TCL came back on and the torque converter locked back up. The rpm's also came back down. It did this three times during about a 45 mile drive on the highway. The truck has just under 180,000 miles. Trans cooler and lines were replaced last June. Fluid recently checked and all was good at that time. I am a field tech by trade, so the truck is probably over maintained by some standards. Any suggestions would be greatly appreciated.

EFI Live 0-90 hp tune
PPE manifolds
PPE up pipes and down pipe
Ryan's Diesel 64mm Supercore Turbo
Banks exhaust and cold air intake
Banks diff cover
Mishimoto hot and cold side pipes
PPE trans cooler and lines
FASS
Stock height with Kryptonite upper control arms and ball joints

Could this be a solenoid issue???

Could it be something simple, like brake pedal return spring allows pedal to sag and hit the brake light switch?

Thanks JohnC, I will look into it over the weekend.
I do like your signature.

The more I think about it, if the brake light switch was being even remotely activated. The cruise control would have disengaged and that did not happen. I now have an Allison service manual from 2000 that shows "Solenoid F" as being the converter clutch solenoid. I recently saw a YouTube video were fluid was leaking into older Allison's solenoids causing issues. Maybe I should just check the external connectors for trans fluid. I don't think it will hurt.