The fireplace flame does not turn on and off at the exact desired temperature. Why?

When the remote is in the thermostat mode (SMART-STAT and RCT-MLT models) and the temperature of the room has not exceeded the desired temperature setting by 2 degrees Fahrenheit or 1 degree Celsius the fireplace will not turn on and off. The thermostat is set with a 2 degree F (1 degree C) range to avoid continuous cycling of the fireplace.