I had the same problem a few times with my drivers-side window. I think it has to do with the design or lack of factory grease. Water, I belive gets in the traks and makes the window stick/jump when going up/down. I say that only because mine came off track only when I had the windows cracked when it was raining (smoker). :o
Lithium grease works well, but you need to get the whole track(taking door panel off again)
Use silicone spray, use it regularly. I prefer once every three months. This way you can spray in the tracks (w/ windows down) and it will work its way down the entire track.
This also works for windows that squeeeeek
