thank you everyone for the input! I do use eco earth, and it makes sense he would get a little red from that.
he was also spending some time outside in the grass and he was digging in the clover so I suppose that could have done it as well?
he has been in the wet paper towel substrate for a couple days now and the redness has gone down a bit! I feel a bit silly for worrying over this if it turns out it was just his substrate, but I'd rather be safe than sorry