THG Heat Tape Concern

[zachsdad]

Hey guys ! I built a home made snake rack out of a pvc shelving unit from my local walmart. For heat im running 15 feet of 4 inch THG heat tape for 4 shelves. I set my thermostat to 90 degrees but the tape gets up to 105 degrees according to my temp gun ! The stat prob is directly on the tape secured with aluminum tape. Even at that the inside of the tub only reads in the low 80's ! The room temps range from 68 - 76 degrees. Is this ok or am i doing something wrong ? Any input will be greatly appreciated, thanks. BTW i will be housing a pueblan milk snake in a 32 qt tub with this setup. The snake is about a year old.