Pink in Red-Eyed Tree Frog's feces... is this normal? Photo attached.

[MantidBro]

What size is his tank? Do you have plenty of branches and other things for him to perch on? I don't think I have ever seen mine touch the ground to get substrate on themselves. I also have the viv floor covered with leaf litter, so that helps prevent that. If they are covered with a lot of substrate when they shed, it could be an issue, but not really likely.