This shabbos, the chazzan in our shul, during mussaf, mentioned the wrong month during Mevarchim HaChodesh. He started out by saying "Rosh Chodesh Kislev..."
Of course, it's a pretty simple mistake to make. After all (as I heard him explain to someone else later on), with all the talk of Channukah, Kislev gets pounded into your brain. It's very counter-intuitive (although factual, of course) that part of Channukah falls out in Teves as well.