Hm? [He looks over at her, and then forces himself not to avert his eyes but focus only on her face.] It's only been burning a few minutes, in another twenty or so it would be hot enough to sting. But right now, it's just really warm.
See? [He holds his hand out, palm up, so she can touch it. Stone is a great thermal conductor, and well insulated, so his skin is very warm but nowhere close to hot enough to hurt even human skin.]
I figured that out for the first time when I picked up a boiling kettle with my bare hand and didn't even notice it until the entire room was staring at me.