Has anything changed inside the enclosure? Anything at all? What about the environment surrounding the enclosure? More foot traffic in view of the tank, more noise, more lights, anything?

My kingsnake used to nose around a lot, too. Not so much that she rubbed off any scales, but it was pretty bad sometimes. She's right next to my desk, and I had been doing a lot of late-night homework when she started with the nosing. I realized the lamp was keeping her up, so I added a sheet of black aquarium background film to the side of the tank, so as to block off the light. Now she's back to nosing around only when she's hungry.

Just one idea, not sure if it can help....