On January 25, I was informed of a precedent from 1980, when the legendary Abe Lerner designed a book called Fond of printing : Gordon Graig [sic] as typographer & illustrator. The book was co-published with the Book Club of California, which lacks the typo (although the Worldcat record suggests the opposite.)
The same informant had the inspired the erratum slip for this pamphlet. He suggested that a humorous slip for such a slip-up works best, and mentioned the erratum for Bruce Rogers' The Centaur (1st ed.). Here's what I wrote, with inspiration from Jerry Kelly and an assist from Paul Moxon (Fameorshame):
Erratum: Digital fonts promise that we will never be short of sorts, but our title page disproves that promise. Surprisingly, the compositor ran out of small cap p in the imprint. While we have always been told to mind our p’s & q’s, we never anticipated that such a deficiency would create a typo for our fellow Typophiles. And so, it is with not inconsiderable nervousness that we ask you to — quickly before someone notices!— insert a p in the imprint of the title page.I'm still annoyed, but I'm starting to get correspondence from very amused Typophiles. (Blush) We should have caught it!