Ford Focus: Frozen stick shift - advice wanted

I have a '01 ZX3 that when it's below freezing the stick is frozen. After
the engine has completely warmed up I can move the stick as if it was
stuck in molasses. Eventually, it reverts to normal. The dealer's answer
was to change the transmission fluid, but that didn't change anything
(outside of making me $179 poorer). This has only started to happen with
this winter. Anyone have clue as to what's going on. I'm not mechanically
savvy so be for I shell out more money, I'd greatly appreciate some
advice. Thanks.
Scott

Thanks, Dave!