Ok, a few things .............
How are you measuring your temps, and humidity ?
Your cool side, or ambient temp is too cool. Ideally, you want it around 80f. 72 is
too cool, and dropping a few degrees at night puts you at 69. I would suggest some type of heat lamp.
I use ceramic heat bulbs for my enclosures, because I live in a cold climate.
You also want to have a hide on each side of the tank, this allows your snake to thermo-regulate
and feel secure at both sides of his tank.