Thanks JLC!

I switched to paper towels because its so much easier to spot poops and pee on them and way easier to clean. So if I can, I'd like to stick with the paper towels now!

Since switching to paper towels I've made sure that the temps and humidity are the same as before the switch (hot side 90*, cool side 80-82* and humidity is 50%). Thermometers are in the same place as well. I have the probe between the glass and the substrate, so its probably that even though the temps are reading the same, he's feeling warmer temps because (obviously) the paper towels are thinner than the layer of bark.

I'm going to leave everything as is and let him get used to it. Would you suggest that if the problem continues after a while that I try lowering the temps?

Thanks so much for the advice.