You should be ok. 98 won't burn a snake, if that's actually the hottest it got. But think about it, you hold your snake without issues and think about your temperature? Doesn't seem that hot anymore right? It's too hot for long term but one night of 98 should not burn the snake. The problem with heat mats and tape is the heat is not always consistent. That's why most like to set their thermostat on the lower side so if you have 5 degree fluctuation, the animal still won't get burned. The problem with no thermostat is they could have a hot spot that gets well over 100. Just get a new thermostat on it before you turn the heat mat back on.