Great observation, the NH polar cap ozone has been well above average for the last several months. This is common during active polar vortex years and we had a very active year with multiple weakenings of the stratospheric polar vortex winds. The weaker west-to-east winds allows more ozone to be transported into the polar lower stratosphere. It's curious that the ozone is still above normal, but then again, maybe it's not too surprising given just how active the polar vortex was this year.