Perhaps, during a spirited conversation about whether or not the Statue of Liberty could be a Weeping Angel ("think about it! someone is ALWAYS looking at it!"), a know-it-all might have told you that said statue has, like a gross penny, only gradually attained its current greenish hue, and would have arrived at Ellis Island resplendent in glorious copper. Now you have something to complain about when purchasing novelty foam hats when you reach old age, yourself somewhat weather-beaten and in less than mint condition.
This is also the the spoiler thread to discuss the mid-season finale of this, a not particularly good season of Doctor Who.