and I have no idea as to why. Very hard 1 to 2 and 2 to 3 shifting. And, it seems to not disengage when I lift off of the pedal. No engine or other unusual symptoms.

I'll need to see if there are any codes stored in the computer and post my findings. In the meantime, any ideas?

most likely bad speed senser

And drives fine today...

Mine did the same thing about a month ago. Pulled the speed sensors and cleaned'em up. Installed, reset codes and it has yet to come back.

As far as the codes, It did save a code but never flashed my SES. Someone had told me that the ECM needs to see the code numerous times before it will flash your SES light.

I did the same last time this happened. I was under the truck fixing the rear transfer case seal and decided to pull them and clean them up. Truck seemed fine after that. How long do these sensors last about? In other words, do they just get grunged up or do the sensors actually wear, like O2 or other sensors that need to be replaced after a while?