I wouldn't worry about it at all- that 'cool side' is quite comfy. When was he last fed? When was his last shed? Many snakes prefer to stay cooler when going thru a shed cycle, but a few days could mean nothing at all anyway- it's normal for snakes to "thermo-regulate" most of the time- in fact, that's part of the reason they get by with not eating all the time as we have to do.We're always burning up calories keeping our big ol' bodies at 98.6*, but when snakes stay cooler & fairly inactive, they don't have to shop all the time for meals.