Sooooo, a random question and thread bump about the whistle bag, since I just picked one up from Holt Renfrew here in Toronto.
I noticed that on the back of the leather tag inside the 2007 whistle bag AND the 2006 monk-style bag that the last 4 digits are 3666 however, I had both bags authenticated by Balenciaga SA's at Holt's 'flagship' store on Bloor.
I have read (several times) on this board that a lot of fake City bags use 5666 and 3666 as the last digits in their serial numbers, but is it possible that 3666 is a legitimate style/serial number for non-city type Balenciagas?