Has Anyone Seen 1970's US Stamps In Vending Machine Packs

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?

Joe

The 90's Makeshift booklets were actual booklets, but the company (MDI) that made them for USPS was also contracted to make vending packs that were little more than folded up blocks packaged in glassines with a label on the outside. I do not know how far back they made them.