The AD reopens and the back is pictured we will know for sure from the reference number, if he still insists it is all NOS (new old stock) and original to the piece I would then email Tag if I were you and confirm everything with Tag.
It could also be that Tag replaced with original parts they had on hand if you check the site Alkiro mentioned you can see the model and picture of the reference.
Regardless if Tag oks the piece and it is a good price go for it, its a nice piece and has held up well