Why is "1930 Graf Zeppelin stamps" trending?

Wikipedia Overview

The 1930 Graf Zeppelin stamps were a set of three airmail postage stamps, each depicting the image of the Graf Zeppelin, issued by the United States Post Office Department in 1930, exclusively for delivery of mail carried aboard that airship. Although the stamps were valid for postage on mail sent on the Zeppelin Pan American flight from Germany to the United States, via Brazil, the set was marketed to collectors and was largely intended to promote the route. 93.5% of the revenue generated by the sale of these stamps went to the Zeppelin Airship Works in Germany. The Graf Zeppelin stamps were issued as a gesture of goodwill toward Germany. The three stamps were used briefly and then withdrawn from sale. The remainder of the stock was destroyed by the Post Office Department. Due to the high cost of the stamps during the Great Depression, most collectors and the general public could not afford them. Consequently, only about 227,000 of the stamps were sold, just 7% of the total printed, making them relatively scarce and prized by collectors.