Chinchilla leaving red wet spots

Hello everyone,

I've had my chinchilla Rex for a few months, from everything I've read he looks like a healthy happy chinchilla. My one concern is that during play time i let him roam in a chin proof room, at some point there are a few red wet spots he leaves behind. I've looked at Rex and he has no cuts or bruises or any injury. This is an everyday thing, i have no idea what it is. Please help.