Here's more of the note posted by Sonus Faber:
Note in the third to last paragraph they say that it has to have been purchased from an authorized dealer not that YOU have to have purchased from an authorized dealer. This is most likely aimed at the grey-market but I would check with them to be sure if I was about to buy used. After all, you don't really know where the seller originally purchased the product.
WARNING
IF A SONUS FABER PRODUCT IS:
1. Directly imported by you from another country, OR
2. Purchased directly from a dealer OVERSEAS, OR
3. Acquired by you from an UNAUTHORIZED North American based re-seller,
ALL SONUS FABER PRODUCT WARRANTIES ARE NULL AND VOID
In other words, you will only be provided a North American warranty on Sonus faber product purchased from a SUMIKO authorized Sonus faber dealer.
IN ADDITION, SUMIKO WILL NOT SUPPLY PARTS AND/OR SERVICE FOR ANY SONUS FABER PRODUCT WITHOUT PROOF OF PURCHASE FROM A SUMIKO AUTHORIZED DEALER IN NORTH AMERICA.
PLEASE CONTACT SUMIKO FOR A SONUS FABER DEALER IN YOUR AREA,
OR TO DETERMINE IF A DEALER OFFERING SONUS FABER IS AUTHORIZED.
Note in the third to last paragraph they say that it has to have been purchased from an authorized dealer not that YOU have to have purchased from an authorized dealer. This is most likely aimed at the grey-market but I would check with them to be sure if I was about to buy used. After all, you don't really know where the seller originally purchased the product.