Silverado shifts hard when hot

[03whitesilvy]

Well I have a 03 Silverado and when it's cold it seems to shift fine but after awhile of driving it starts to delay then go into second gear firm not really hard just firm it's bugging me the delay that it has I was thinking the tsb for the 1-2 accumulator valve kit but mine only does it when the tranny heats up any ideas? Only does it at light to moderate throttle and tow haul mode seems fine also

No checking engine lights