Whats the temp of your pad? If i had to take a guess its around 93*?
What brad also? Are you using a tstat?
See if your pad is 93* then he has a hotspot of 93*
Say he gets to hot he will move to the other side.. But then he has this hot lamp baking down on him at 94*
So he has no way to thermo-regulate if he gets to hot seeing as both sides are hot just one is above heat one is below