10hPA is a little to high up to have much of an impact on the Tropospheric Polar Vortex. With Sudden Strat Warmings, they tend to start at the top and then propogate downwards through the atmosphere. Once it reaches 70hpa and above then you start seeing interactions of the warming with surface conditions. So don't worry too much about its location at the moment, there's plenty of scope for that to change over the coming weeks.