The D700 is 7 years old. It would seem strange to only now detect some issues with it.
If it was one type I'd be suspicious but 4 types and only 100 of the D7100 seems strange. Maybe they, at the same time, try to subtly make people register their products.
They communicated openly about issues lately so I don't see why they suddenly would do something sneaky. They're even doing recalls for problems none knew existed.
It's just with these things; bad vibes travel faster and wider. Until proven otherwise, I don't see anything negative behind it.