[Frank Miller]

All air holds some moisture. If water was forming on the metal due to change in temperature, I'm surprised he did not notice the paint or primer not laying down properly. Just to be clear when the weather gives you the dew point that is the temperature when moisture from the air starts to condense. The higher the humidity the higher the dew point. Air dryer's performance is measured by the dew point of the air. So -40 air means you will not see moisture until the air temp is below -40. If the dew point is 50 and the temp of the metal is 50 then the metal will cool the air around it and result in moisture.