I notice this with mine, too. He'll rearrange the substrate to get as close to the glass so I just cleared that area and put paper towel on top of the glass so he has a clear spot to curl up in! For now, I don't think I'll be needing the RHP as my room stays at 75-79. It's been constant at 77F the past few nights and that's with the weather outside at ~35F at night.