Here's how I see the latest annual Arctic sea ice extent rankings using the latest data that I've just downloaded ending on the 15th of September.
And here's a snapshot of what the data file looks like that I download just to prove to myself I'm not going mad.
All these daily values translate into the following chart with the minimum occurring on the seventh and not the tenth of September.
I have monitored polar sea ice using data from the NSIDC for almost five years now and never found much problem until June of this year when the NSIDC transitioned to using data from the DMSP F-18 satellite due to issues with the F-17 satellite. I'm now totally confused, I realise that all the differences are very trivial when you are dealing with millions of square kilometers of ice, but I still wonder where I'm going wrong, If you know then please drop me a line!