This may be normal. The coldest thermostat setting on your dial(other than the "off" click) correlates to about 62.5 degrees F. The climate system will deliver full heat until your 40 degree interior reaches 62.5 degrees then will modulate the water flow valve and maintain that temp.
You need to do an extended drive to see if that happens. If you still have hot vent temps and interior is hot then there is a fault with the climate control system.
A repeat of my old post-Bottom of blue zone is 62.5 degrees, top of blue zone is 70 degrees, 3 o'clock position(middle of white zone) is 75 degrees, middle of red is 80 degrees, top of dial is 140 degrees. Doktor A