Your internal temperature is 98.6. Your skin is actually much cooler on average. 98 degrees over an extended period of time in unhealthy for a ball python. It might not burn them in the sense you're thinking of (blisters, etc) but it isn't good for them. Now, if your unregulated heat mat gets to 130 degrees, it most certainly can cause severe burns. I've seen reptiles with burns from them.