BlueEyesAtNight,
It's not a problem he doesn't move when he deficates, but if you see it you should still remove it. If the coloration seems to have faded, or if it's so light that it is difficult to remember, then he's almost surely fine. As I said, it's good that he's eating, just don't feed him mice too often (only once every ohter month or so) as they tend to be high in fat and can lead to a host of health problems. Best of luck to you.

EMWhite