I came across a sealed package of five 10-cent Robert Frost stamps (Sc# 1526). At first I though it was some dealer's packaging but when I flipped it over I saw an imprint that said it was a 'Vending Machine Pack'. Has anyone seen anything like this before? I know booklets were sold in vending machines and I know in the 1990s there were makeshift booklets made for vending but this is the first I've seen from the 1970s.
Can anyone offer any insight?