Choices. Im finding thats the key word in caring for snakes, giving them enough choices within there enclosures and than letting em do their thing. So if the heat under the heat pad is a little uneven, that means more choices your snake can make,provided of course he can get to those various spot while still feeling safe. Its amazing to me to see Plissken scoot over just an inch or two to get a little warmer or a little cooler,its almost like him saying "aahh thats just the right spot."