In that case the thermostat does it's job in getting the engine to operating temp right away so it runs more efficiently.

It is unlikely the thermostat is defective; one possibility is it could be calibrated to take into consideration that the mixture being used is a water and coolant mix rather than pure water (coolant has a higher boiling point) so when it reaches a certain temp or pressure, it is assumed that the mixture going through it isnt boiling yet (i'm just guessing on this here. ).