YES! Even the 1-5gal mini ZooMed mats can get to well over 100f without a rheostat or thermostat. I know this because I have the mini ZooMed mat, and have measured its heat with a digital thermometer. It was over 110f in spots. I have to turn it down half way with a rheostat to keep temps at the 90-93 range.

Make sure you are measuring temps with an ACCURATE digital thermometer. The Acu Rite brand can be found at Walmart, Home Depot, or just about any other large box store, or hardware store. They run about $13.

My ambient house temp is about 74 degrees in the snake room, so it is definitely not a house temp issue. Be careful!