Eh. Was it really? What about 2010, when they played a setlist consisting almost entirely of post-2000 songs? Or 2006, when they played their entire new album? Not to mention various tidbits, like having Moonchild in the 2008 setlist, Lord of the Flies in 2003, no Fear of the Dark in 2005... in 2011, everybody expected Brave New World to be in, which it wasn't in the end. Sure, Hallowed being out was unexpected, but I don't consider it the most extreme case.
Maiden really aren't as predictable as many people make them out to be.