If this sort of thing can happen to the world's most high-profile writer, with her very high-profile new book, it can happen to any author, any book, any publisher. In fact, I can tell you it is happening to a great many ebooks bought and sold at this point in time. For good or ill, this is the general state--i.e., not particularly dependable--of this technology at this moment in time. It's getting better, but I think everyone involved should be realistic about where things stand at this moment, and mindful that publishers and retailers are trying to improve things.
"Yesterday the eBook file for The Casual Vacancy by J.K. Rowling was released to all U.S. eBook retailers. There were issues with that file, including the adjustability of font color and size and adjustability of margins. As soon as Hachette was made aware of these issues, a replacement file was uploaded to all eBook retailers. Hachette has requested that each retailer contact their customers directly about reloading their eBook.