I believe your car takes TiV - (mobil 3309) fluid which is a bit thicker and has a friction modifier to take up for the partial lockup that this transmission's torque convertor can do.
I have heard of many people complaining of this issue after a change, There are 2 shifting solenoids which take care of shifting through the 4 ratios, one for the torque converter lockup control and one force motor (aka pressure solenoid to control the shift aggression and line pressure depending on the engine load and rpm.
For kicks (free of charge) do a reset as recommended, make sure the ATF is at right level (check it when HOT only) adjust as required and check again for the problem.
If it does not help then take it back to the dealer and smack them on the head. (you took the car in for a lube exchange of the transmission and the car was behaving correctly as toyota says - after the service procedure the car started to behave incorrectly - according to toyota manual - its their headache to resolve, make sure they dont try to arm wrestle you out of it)
btw the ATF is checked in Park or Neutral ONLY.