I've been in the process of installing air suspension which requires the removal of the battery to access a grommet in the firewall. I've had to do it the past 2 weekends. I've noticed that driving the car after putting the battery in, the transmission seems like it has to relearn shift points or driving habits. I've noticed that it'll hold 2nd gear for a long time or randomly downshift aggressively when it's not needed. Then after a couple of hours or driving the car around a few times, it goes back to normal. It has happened both times I've completely disconnected the battery. I have the 8-speed transmission.

I wouldn't expect that disconnecting the battery would reset ecu like that. All the electronic memory settings don't reset or the radio settings.

 

All of my cars have acted this way. Probably common on OBDII vehicles

 

Yes, one of the only DIY methods for resetting the ECU is to disconnect the battery for at least 10 minutes or so. I did this a few weeks back and yes, the car does act a little funny at first while everything begins to relearn and reset. My car has VGRS and even the steering was a little strange for the first few turns. My transmission didn't do anything strange like you mentioned but throttle response and shifts were more crisp. Now that it's learned my driving style again, everything has smoothed/softened out.

 

The transmission does not have the ability to learn because it gets all its signal inputs either manually (from the driver) or from the engine by means of its ECU. Whatever different sensation you are experiencing after disconnecting the battery is likely the result of the engine's ECU readjusting.