I discovered this phenomenon almost a year ago, when I ordered my copy of Lion Rampant - also from Books Etc - having failed to notice it was POD. It was news to the author when I brought it up on his forum.
More recently, I bought IHMN from another Amazon seller, and received it promptly, but after waiting more than a week - I know, terrible, isn't it? - for Heroes, Villains & Fiends to be posted by another seller, the normally very prompt Wordery, queried why it was still 'preparing for despatch', and received a reply quoting the text I had missed, to the effect that it was POD. In my defence, the text in question could only be seen by clicking on 'read more', which had seemed unnecessary, as it was clearly stated elsewhere in the listing that it was in stock. I asked the seller to explain this contradiction, but received no reply. I cancelled the order.
Oddly enough, I don't experience this sort of delay with Lulu, from whom I received a book today, less than a week from placing my order.