Your body temperature is likely around 98.6 so 100 is barely warm as said you cannot accurately tell temps with your hand. Also as stated the hottest place inside the enclosure should not exceed 94º and at that personally say 92 is the hottest given the variable accuracy or most temperature devices.

If you switch to paper towel watch out that if you feed in the enclosure a damp rat can stick to the paper towel. It is a freak accident but my vet last year did a surgery on someones snake to remove paper towel from its stomach. Keep an eye on that.

What substrate are you using? Some have greater insulating amounts than others. What hides do you have? Have you checked the temp INSIDE the hide. Often it will be 2 or 3 degrees more than the warm side substrate.