I contacted them and they're mailing the book air mail today. Dunno what happened there - no apology, no explanation, but they are always good on their word.
When I first signed up I contacted them as I hadn't received a magazine for several months (like now) and they sent a new copy. I ended up with 2 copies of the original mag... My first Zymurgy of this subscription was mailed on April 20, 8 weeks after signing up. Will be another 3-4 weeks based on past experience.