So I changed my thermostat and thermostat housing gasket yesterday filled it up with antifreeze and drove around no issues. Well today I smelled antifreeze so I checked and it had overflowed temp stayed normal. So I cleaned up the mess and continued to drive beat on the car a little and no more came out. When the car was hot the coolant level was where is should be, when the car cooled down the coolant level dropped to a little under halfway down the reservoir. Should I add more coolant or just leave it?