A surprising report by Gerrit Wiesmann in the Financial Times says, “Random House, the world’s largest book publisher by sales, could keep its books from Apple’s iPad when it goes on sale next month, as the Bertelsmann unit fears the effects of the tablet device on the pricing of electronic books.”

Yes, while the other five members of the exclusive Big Six of American publishing — Macmillan, Simon & Schuster, Hachette, HarperCollins and Penguin — are all believed to have deals with the iPad’s iBookstore, Random House has been the lone holdout. And, says the FT report, “the absence of the book market leader would prove a blow to Apple. Markus Dohle, Random House chief executive, did not exclude the possibility of reaching a deal before the iPad goes on sale on April 3, but said he was treading carefully, as Apple’s pricing regime could erode established publishing practices.”

In a post on Publishers Lunch (subscribers only), guest blogger Sarah Weinman notes that, well, that’s “the whole point.”

Meanwhile, Dohle says the Apple deal — that is, the agency model — meant “changes, in particular for our stakeholders,” which meant in turn that Random needed to have further discussion with its authors and their agents.