Not an error. Something is going on...
http://www.independent.co.uk/environment/arctic-antarctic-sea-ice-polar-global-warming-climate-change-india-alaska-a7458881.html
Does that main max in the late part of the year happen because the Antarctic sea ice is just passed its max plus the Arctic is supposed to be rapidly freezing up? If so, I'd wager this is a combo of the wholesale lack of sea ice in the Arctic plus a paltry (relative to normal) level in the Antarctic.
Here's the EST equiv for the UTC times in the models:
0z = 7pm EST (-1 day)
6z = 1am EST
12z = 7am EST
18z = 1pm EST
I guess that's one good thing about working for a British company.