This is the thermostat I use... It probes and is real close to the heat mat.
So it mus be a few degrees cooler above the repti-bark.

http://i46.tinypic.com/2wovb6g.jpg

http://i45.tinypic.com/14ty44z.jpg


That's temp and humidity now with the light off.
The probe is still halfway under the repti-bark.
I putmy hand onto the repti-bark and it's warmish... Not hot.