Depending on your thermostat, the temp of your basking area could vary during warmer and cooler times of the day. I would place the probe on the bedding instead of taped to the glass, or maybe bury it in the bedding a bit, it could be warmer down there, and your snake can easily manipulate the bedding to that he can get closer to the UTH. 88 degrees is also not a bad basking temperature.