New max HR

Well this is notable. I've been training with a Cateye CC-HR200DW since my birthday last year (which is a great computer for the money by the way), and my max HR has always been 185. In the heat, on sprints, hillclimbs, warmed up, not warmed up, cyclocross, crits, whatever: always 185. Today, however, during the Cat 6 weekly hills-n-sprints ride, I hit 187 going for a town sign. Heart rate is so complicated I'm not sure what to make of it, whether it's a good thing, bad thing or that's just the way it is. I don't compare my max HR to others' because I know at least that everyone is different, but it is interesting that it changed after a year's worth of every opportunity to peg my max HR.