Hard Shifts

[Duraman]

I have a 2003 GMC 2500 HD 5 speed auto 245,000 km's, tranny flushed 1000 km ago, recently started to have harsh down shifting, hard enough to skid the tires.... most noticable in the lower gears of course 3rd rough, 2nd hard, 1rst skid the tires. Weird as this may sound if I shut the truck off, wait a bit, then restart 8 outta 10 times it will now shift normally    is this something that you may have seen before or should I start saving for a tranny job ?