Not sure, but i HAVE noticed this in the past few weeks:
Right now, when i first start it up cold and it's cold outside and the rpms are about 2000----because it's on high idle, when i drop it into gear (either D or R), it sort of gently engages. It doesn't grab real quick. (which is good)
However, a few weeks ago i was having problems getting my rpms down to normal because of a choke linkage/fast idle cam problem/out of adjustment. So after i would drive the truck for a good while and the truck and drivetrain would be nice and warm, i would park it briefly, say to get something to eat. Then when i would start it up again and put it into gear, it would slam pretty hard into D or R (which i thought was bad). Remember now, the rpm's were not normal, they were pretty high in neutral----like 1400-1600.
As far as actual shifting from 1-2, 2-3 etc., i don't notice much difference when the truck is cold vs. warmed up.