I believe the stocks for the kickstarter and those for the store are handled separatedly. There were some unexpected delays (which they warned us about in an update) for the kickstarter books, so they knew they were going to miss their first shipping date (and again, they warned us). They sent another update just today to say the kickstarter books were about to be delivered.
Futhermore, it's actually pretty frequent for kickstarter project to have the store version becoming avalaible before all backers have gotten their order. Logistics works in mysterious ways.
(Also, I doubt anyone at hiveworks read this forum, but I could be wrong).