shr0pshire: Here is my idea of why returned the queen to the original square.2. Qa4 is an unorthodox opening trying to get black to make a mistake in the opening, or get black out of the book. Instead black just develops while subtly attacking the white queen in the process.
By move 8 white realizes his queen is jeopardized. So white now needs an escape plan for his queen.
He thinks Qa3, he thinks what am I going to do with her majesty after that. She will be lonely and in an awkard area of the board. She can be vulnerable because there is not an escape for her here either. A bad placement for her majesty.
The other option is Qb3 and no one really likes that. That allows Na5 and other developing moves that will kick the queen around, while black eats up space and gains tempo.
All other moves with the queen allow for emminent capture of her majesty, so the best spot for her and for her safety is to move her back to her original square Qd1.
Again the reason for the original move of the queen on move 2 is to get black out of the book, so that black (the stronger player) doesn't use his pet system.
Although it doesn't have looked to cause any considerable weaknesses in black's position in the opening, white played it well and won with it. So mad props to white!