Guess that one word in 120,000 must have slipped through me and three sets of editors. It's difficult with a series when you're writing a book a year to get every last word right I'm afraid. But it should have been picked up.
Also if God can come up with fluffs like the ones below I think mere mortals are allowed one every now and again.
http://en.wikipedia.org/wiki/Wicked_Bible