I visited the Winterbash 2013 hat overview page, logged in and noticed my avatar (displayed next to the logout link) wears no hat, even though I wear hats for all sites.
This is by design. Could be a feature request to make it sport your hat, though I expect it'd land fairly low on the priority list. Unless it's ridiculously easy, in which case it'd happen in about three seconds. But if that were the case, it'd probably have been done already. Unless it was an oversight, in which case a feature request would help. And down the rabbit hole we go...