This doesn't happen very often. Usually it happens when a large number of fans comment and blog about how they want the release date moved up. But that's not to say you should pester your favourite authors. In fact, they usually don't have any control whatsoever as to when the book will be published (other than when they finish writing it, obviously.)
Point is, that Out of Sight, Out of Time will now be release on March 13, 2012. Be happy. Jump for joy. Run around in circles. Just remember: next time you're on Ally's (or any of your favourite authors') site, be sure to thank her. Tell her how much you love reading her books and how much you appreciate her efforts to write the best she can. That's all you can ask for.