Are the Nikon lens kits bought from Amazon ever "gray", with limited warrantee?

Yes there are some gray market lenses...they will usually be advertised as "International version with no warranty" or it could be that in the Amazon Market Place from 3rd party advertisers its not mentioned or stated but usually Amazon will try and let you know through their main web site if it has no warranty...

Yes, almost all camera gear sold on Amazon, especially those by 3rd parites are grey market. If the seller (including amazon.com) is not an authorized Nikon dealer, then it's grey market. Nikon has two levels of dealers: amateur and pro. If the seller is not a "pro" dealer and you buy a "pro-level" Nikon product, you will have no warranty. If the seller is not an authorized Nikon dealer at all, then you will not have a warranty. Even if the warranty card says USA on it, if the camera was not bought from an authorized Nikon dealer, Nikon will not honor the warranty. How will they know? Easy. You will have to supply a copy of the receipt with all warranty repairs. The people at the Nikon authorized service center will check to see if the product was purchased from an authorized dealer.

Best thing to do is to completely avoid amazon.com and just buy from an actual camera shop in your area, or better yet, go to adorama.com or bhphotovideo.com. Both Adorama and B&H are highly reputable camera shops out of New York serving amateurs and the worlds best professionals. Amazon is filled with 3rd-party vendors that sell kits filled with junk that are either not compatible with the camera or you simply don't need. Not so with B&H and Adorama. Both B&H and Adorama sell USA and grey-market gear, but they state it plainly which is which. And unlike amazon, you don't pay sales tax if you live outside of New York.

Both sites have identical pricing for Nikon gear because Nikon has fixed the pricing. So you won't find Nikon gear being sold at any other price by an authorized dealer. That's one way to find out if the product is grey market. Since Nikon prohibits authorized dealers from advertising pricing other than what THEY SAY, if you do see any Nikon product for a different price, then it's not being sold by an authorized dealer and you should be highly cautious.