Be very careful!
Tony,
I didn't see anyone else mention this so I will:
Is the thermometer located in the upper-center on the tank the one that you are using to monitor the temperature? If so, you are likely overheating your snake, especially if you are using both a heat mat and a lamp. (Are both heat sources under the same end??)
In order to be effective, the thermometer needs to be under the lamp (and on top of the mat) on the surface of the substrate. The temp difference between the heated tank floor (where the snake resides) and the lid of the tank can easily vary by more than 20-30 degrees.