All of my thermostat probes are held in place by aquarium grade silicone. If you have probes inside the enclosure where your snake can get to them and they're not secured somehow, odds are they'll get moved. Probe placement obviously has a lot to do with how well our thermostats work, so if that probe gets bumped 6 inches to the left, your thermostat is going to think you need more heat, and then you run into the issue you're having.
Essentially you need to find a way to secure your probe or your snake will move it and regardless of what thermostat you use you'll get whacky readings. DO NOT put tape or anything that might stick to your snake inside your enclosure. Again, personally I like aquarium silicone and I've been in that hobby so long I always have plenty on hand. It's inexpensive and easy to use.