Do you have something to regulate the temp of your UTH like a thermostat? Without one your UTH can push 120 ° which is WAY too hot and can burn your BP. Always make sure you know exactly what temp your hot spot is running at!

From the sounds of it his hot spot is either too hot, or he just doesnt feel like using it atm. BP's can often be content for a few days in one place once they find a good snug spot. Especially if hes new to your home.