I dont think its a customs thing, they are no more likley to pick up a Nikon camera than a Canon or any other make.
My money would be on Nikon doing something, for a while now official Nikon stockists have been low on stocks of some models, Nikon have reduced production volume, when some one goes into a Nikon dealer to buy a camera if they haven't got it and cant get it quickly they will try to sell another make, thus lost sales for Nikon.