That high humidity is exactly what your snake likes. You just don't want the substrate WET. Substrate can be moist, especially during shed cycles. I think your set up is a good one. If you haven't already done so: Make sure the UTH doesn't get too hot---use a thermostat or reostat.
The high humidity is a sign of warmer ambient air(warmer than the air in your home) which is also good. The warmer air holds more moisture.
If that is one of your snakes under your user name, its a looker.