Temps of 99.4 are obviously not enough to burn a snake (remember that your own body temp is 98.6 ) however the temps might have gotten higher especially if your heat source is not being controlled.

Do you have a thermostat to maintain proper temps and prevent over-heating?

If not get a thermostat before an accident happens! And if you do lower it down some 99.4 on the warm side is a bit too high for a BP

As said previously pink belly is also the sign of shedding.