Yours is a very important comment, even if it doesn't propose the explanation for the "cooler" metal. Your comment reveals how important it is to understand the problem. The lack of understanding is a bane to the engineering field! (Though, it is a gift to some physicists who love an excuse to bust the chops of engineers, a la Sheldon Cooper.)The foul temptress of expediency of thought occasionally seduces engineers into spouting off solution methods that are associated with the problem. They can do this without actually confirming that the solution method is truly applicable. As you pointed out in this case, the solution of "explain the cooling by conductive loss to the air" could not apply since the air was hotter than the metal. (Also, eEven if the air were cooler, it would be in order to do a scale analysis to see if it was the primary issue.)