I'm glad it's not that serious and hope it stays that way.
I know that sometimes when Zeus eats something he shouldn't, he gets bright red in his poop. I freaked at first but vet said it was not blood. My friend's son had the same thing happen to him when he was a baby and his body was processing banana like that - bright red. So I think the same happens with Zeus. It just how the body processes certain foods.
Still no less scary though...