[A4] door not locking or unlocking with remote

[JeffR]

Well a few days ago my back left door would not respond to my remote 
(wether it be to unlock or lock) and i had to lock or unlock it 
manually, which was sort of a pain.  i took it into my local audi 
dealership and they said that it started working for them and that maybe 
some water had got in there and frozen it and then thawed when they got 
it into their garage (i keep my audi garaged so i doubt that).  it 
sounded a little wierd to me but when i got it back from them it worked. 
they said they lubed up the door lock but i just thought it was a little 
strange. any thoughts?

-jeff
2000 1.8t