My controller warms up when I heat up my Mini Gray mat. Is that OK?

It is OK for the controller to warm up when the mat is heating and N.P. the function is activated. 

We recommended using the N.P. function of mini mats only on low heat settings or without heat at all. 

If you would like to use both N.P. and FIR heat, you can also do it sequentially. Start with N.P. 30 minutes procedure, and after this, switch your mat into heating mode.