I've got 06 TL auto that has been lately short shifting when in automatic mode. It would short shift instead of revving it out, on the 3-4 shift.
Is this early sign of a tranny that's going out or time to get 3rd 4th gear pressure switch replaced?

 

you need to much more specific about what you are describing as short shifting man.

 

The shifting is controlled by the throttle position. If you're barely pressing on it, it'll shift early for sake of fuel economy.
Also pressure switch & filter is always a good idea if you don't know the history of the car.

 

Yes, the shifting pattern also seems to change depending on if there's an incline or decline.
I guess this is just how their Grade Logic transmission works.