Steinbeck Pigasus

[TylerHG]

I'm not sure if this is the kind of post that should be on here, but I am wondering if anyone knows about the pigasus in Steinbeck books. I.e. were books actually ever printed with a pigasus and the Latin quote "Ad astra per alas porci"? Or was this something that Steinbeck only did while signing books? If books were actually printed with this stamp, around what time periods was this done? Much thanks.