Honestly, you'd be surprised what the temperature feels like that would cause a burn to your BP - it doesn't really feel warm to us at all. Hands are a pretty poor indicator of the temp range these guys need. A heat pad plugged into the wall without a way to control it can easily reach unsafe temperatures in a short amount of time. If he's completely avoiding the hot side, I'd venture to guess there's a reason why.
You should probably spend a few bucks on an infrared thermometer (a good one can be bought at a local pet store or online for less than $30) so you can be sure of your husbandry.