My Mashes have gotten so much better since I bought a ThermaPen some 2-3 years ago. I love the thing. Although, last batch, my pen said I missed my Mash Temp by 3 degrees. 3 DEGREES!!! So, I will be brewing tomorrow, but I am going to change the batteries in the thermapen for this batch. If I am still being told that I am missing my mash temp, I'll be looking into my HLT Thermometer. But my question for you is, have you ever lost faith in your thermapen?