I am guessing this is a small (baby) snake? Typically they tend to like it cooler. Snakes like most animals when the muscles are working it builds heat. Little snakes this seems to effect them more than others likely because surface temps effect the core temp more.

Also all digital thermometers have errors, some have more or less. This is rated in the specs +/- _ºF or C (or a % for better units) this figure represents the quality of manufacturing and quality of materials mostly. The better the materials used and the higher the standards of manufacturing the lower the error is. The cheaper thermometers often are +/-2ºF this is super common (the only accretes were +/-2ºC close to 4ºF off, I don't know about the new ones check your specs) I always recommend calculating this into your temps.

You read 90-92ºF if we guess 2ºF in error, the most common in low end thermometers, we see 88-94ºF. 94ºF is quite hot I don't personally keep any royal this high and personally I keep baby snakes at 88ºF.

I would suggest just dropping the hot spot temp down so you see maybe 87-89ºF range rather than what you have.