>I don't know if that holds up. Mine is US and is 50xxxxx, and >apparently some in Canada are the same.
No, yours is not USA. Yours is Canada and technically Gray Market. Your registration means absolutely nothing. Registration is for the company to know where to send you promotional material. Same thing for the warranty cards. Means absolutely nothing. Now that is the rules. But some rules can be bent. As long as you bought the camera from B&H with receipt that does not say Gray Market Nikon will honor the warranty. If push comes to shove you can always send it to B$H for warranty repairs. To get warranty repairs in US you need receipt from an authorized dealer and nothing else. And sometimes using receipt from any dealer in US works too but it would be at Nikon discretion.