I think you'll find this is a blip due to the fact the iP5 was launched so close to the holiday season. Apple sales always peak in the months right after a launch because so many Apple-ites have been holding out for the new model.
The picture was probably also distorted by the fact that no major Android player released anything really new (the N4 can't really count, given the lack of stock).
In the whole of 2012, Android was bigger than all other phone operating systems combined in the US (51.8%) and almost double the size of all other phone O/S combined in Japan (64%).
Think those percentages meet pretty much any reasonable definition of dominant.
The latest iPhone usually has the highest market share for an individual model in most markets, though the iP4S lost that briefly to the SIII in the months before the announcement of the iP5.
One of the many reasons why Apple's share price has dropped 30% in the last few months ..