I noticed this same thing last year. They seem to lock down the fares until after 1/6 or so, and then release the lower fare classes after the new year rush is entirely over. The cynic in me says this is to keep people like me from benefiting from the inevitable random mileage bonus they offer in December for booking flights in that month. I'd like to see my family in the slow period of Jan and Feb, and the fares area always dirt cheap...but now I have to wait until the bonus is gone. Oh well.