iPhone 3G, OS 3.1.3

Since OS 3.1.2, I've been having a problem with boss paper, in that everytime the phone resprings, the wallpaper, whatever it may be at the time, will stretch out vertically. I have the aspect control set to zoom and before the respring, the pic is proportionate. After, however, it becomes skewed.

Checking the bosspaper settings shows that the aspect control is still set to zoom. Fixing the problem until next respring is easy; cycle through the aspect control choices back to zoom and exit to homescreen. But I'm looking for a more permanant solution.

I've got screencaps of exactly what I'm talking about...

Thanks in advance.

Before respring: