where are you measuring the temperature? on top of the substrate or at the glass adjacent to the heat mat? you want to check it at the heat mat directly adjacent to the glass as that would be the hottest spot your snake can touch. but as bcycling says - you really shouldn't even run it without a thermostat. what's barely warm to you is probably somewhere in the 90's or higher. if you do keep running the heat mat, make sure you have a hide on the cool side so she can go over there.