My passenger side window seems to do that sometimes. Close the door, open the window all the way and close it a few times. Cycling this will get it to relearn its position.
I've also found mine sometimes forgets that it's down. Usually the process Chris notes works, but once it was raining and water was pouring in and I couldn't get it to go all the way up no matter what I did. It's like it thought the door-open height was actually the fully closed height, and every time I opened the door the maximum height of the window decreased a little bit. Really bad news. Steering wheel reboot did nothing.
I found a garage in which to seek shelter and called Tesla. They advised some alternative reset process: my memory is a bit hazy, but I believe I had to manually power down the vehicle using the center console's emergency power down button, quickly exit the vehicle and close the door, walk out of proximity key range for at least 45 seconds, and then return to the car and open the door. That worked.