Tranny troubles???

[LtE-36]

My 2003 chevy 2500hd 4x4 w/6.0 gas engine 41000 miles

felt like the tranny slipped when leaving from a stop, the rpms went up but the truck barely moved. It almost felt like the wheels were spinning but they were not.

Any ideas?? It has never done it before and it only did it that one time so far.

[GM-Tech]

There's a TSB on this condition which basically says update the PCM calibration. Couldn't say if this is your issue or not.