If the heat in your home exceeds the set temperature the Thermostat is set for, then there are two likely causes.
The first thing to check is to see if the Thermostat has become crooked on the wall. Just looking at it should tell you. If you believe this is the case then take the cover off of the Thermostat, and loosen the mounting screws that are holding the Thermostat to the wall.
With the screws loosened, adjust the Thermostat so that it is level, and then retighten the screws and replace the cover. Take the time to check to see if the temperature is still gets higher than the settings.
Another possible cause is that the thermostat heat anticipator is out of adjustment. This little unit is located typically in the center of the Thermostat. This unit basically controls the furnace and tells it at which point it should turn off. So if this little device is haywire the heat in the house could well get to be too high.
Our best advice, if you suspect this, it to call your Longmont, CO local, licensed heating specialist and have them examine this problem.