That's most likely the thermostat opening 210 deg., so that's what it should run at unless it's under load during towing or a hot day..
You can lower that by installing a 180 deg. or 195 deg. stat and tuning for it. It will run cooler, lower the under hood temps, possibly make more power and increase mileage. I have the 8.1L and changed mine to a 180 deg. and have electric fans that are set to 195 deg. so it stays in between 180-195 deg. unless I'm towing and pulling a hill. Then maybe it will get to 200-210 deg.