I can only imagine that this was a planned move by Sony, since they know that the price cuts lead to sudden jumps in sales.
With the price cut in October and Call of Duty and Star Wars Battlefront in November, I think the PS4 is deliberately attempting to maintain dominance in what much of the media and Microsoft claim should be a Holiday season that massively closes the gap between the two platforms.
At this point, I think it's up in the air between PS4 and Xbox One regarding who will win the October NPD, and with Halo coming at the end of the month, that is not a good situation for Microsoft.
If PS4 wins the October NPD and the November NPD, you will definitely see major news sites proclaiming (undeniably prematurely) the death of the XBox One.