Mine was several years ago when I purchased a postage lot for use on our mailings of EzStamp. While my daughter was putting stamps on a package, she notice something odd about one of the stamps & she brought it to me. I almost fell off my chair. It turns out it was a major error – Missing Silver Inscriptions Sc#727a. I went through that postage lot carefully and found another gem shown in this photo. More on that later.