True. I have seen toads legs becoming red like that, it went away after a few days. I think if they sit on cool ground for awhile their legs can turn red like that as well.
Do you use the zoo med eco earth? I have never noticed that it can stain my hands; although I do get a lot of dirt on them when breaking up the brick when it hydrates. My toads tend to be covered in the stuff after burrowing.