Trans shifting hard

I have a 2000 Z71, 5.3 engine with 100,500 miles, original trans (not sure which one though). This morning on the way to work, after the truck had warmed up it whenever I stopped shift from 1-2 and 2-3 were hard, 1-2 being the worst. It didn't give me any kind of warning lights or codes.

Is my trans on its way out?

This needs to be scanned with a trans function scanner to look at solenoid functions and a possible stuck pcs, or pending trans codes.