Only thing that comes to mind is the window does have a small space left open when the door is closed and then it will close the rest of the way after a second or two. Could it be that the small indent is not closing all the way? You could check that by standing outside the car on the passenger side and observing the window glass after closing the door to see if it does close up all the way. There is an adjustment that the dealers can do if the window gets out of adjustment and fails to seal completely against the rubber insulation. Good luck with your problem. Hope you can get it sorted.
2014 M6 Singapore Grey
2013 650iGC M Sport Black Sapphire Metallic
2012 650i Black Sapphire Metallic-Sold
2011 535i Sport Black Sapphire Metallic-Sold
2008 650i Space Grey-Sold
2007 335i Space Grey Coupe-Sold