How hot does 11" 20 watt flexwatt normally run?

I built a rack like Pwilliams58, and decided to use 11" flexwatt, because that is what Reptile Basics sold. I built the rack out of 3/4" melamine, and used 28 quart Sterilite tubs. I altered the rack by installing a 3/4" melamine back that I taped the flexwatt to. My flexwatt is running at approximately 110 F, but my hot spot in the tubs are only reaching 87 F. The flexwatt is running at 100% power.