Dodged a bullet, or, at least, I think I did. Wiggles managed to squeeze himself between his RHP and the ceiling of his enclosure.
The RHP was on. I know the temperature on the surface of the RHP can get as high as 145F. It's usually safe because the snake isn't supposed to be able to lay on it. Wiggles was able because the screw that secures that side of the RHP to the ceiling fell out, and I neglected to replace it. I've replaced the screw and the RHP is, now, secure.
Wiggles isn't showing any signs of injury. No sign of a burn. I've been watching him all evening. He's been moving and behaving normally. Looks like I got lucky.