Thankfully we have our own resident Poop Scene Investigator!
You're probably right, I have one other thread talking about it. He's very skinny and was dehydrated, so I think it is a product of his rehydration. I don't know what's up with him now. He looked dull then brightened up but now his belly looks pink. It's like he's only gonna show one shed sympton at a time or something, silly boy!