2001 Other Jeep Models Whiney cold tranny

I've recently purchased a 2001 Grand Cherokee Limited. Among a myriad of other issues, which I might get to in a separate posting, I've noticed that on very cold days (20 degrees F or so) I get a pretty decent whine or whistle from the transmission after a cold start. Sounds almost like a turbo. Once the truck warms up for a few miles is seems to go away. If it's normal then I'm not so concerned as it sounds kinda cool anyway. If it's a hint that the tranny is on it's way south then I'm quite concerned and is there anything I can do to avoid total destruction? Thanks!