Buck said the Te Mata wines were often served to visiting dignitaries at state functions, including royalty. Their use at the dinner was because they were part of a programme to promote the country's finest wines, run by Air New Zealand - which helped organise the event.
Buck said he understood Air New Zealand had whittled down the wines in the programme to a small group to be served tomorrow night.
"I think it's a great endorsement for New Zealand wine as a whole but Hawke's Bay in particular, and the wonderful wines we grow in this region. When people select the very best of New Zealand wine, so often they end up coming to Hawke's Bay."
Another link is MC for the evening, poet laureate Selina Tusitala Marsh, which Buck said was an award Te Mata Estate established in 1997.
Craggy Range CE Michael Wilding said: "It is such an honour to have Craggy Range Sophia and Le Sol representing Hawke's Bay and New Zealand, and being served to Barack Obama and others at such an amazing event."
Napier Mayor Bill Dalton was reportedly among the select few New Zealand mayors invited to attend the dinner, but he has said he was not invited.
The others included mayors of Auckland, Wellington, Hamilton, Palmerston North, Christchurch and Nelson.
Dalton said he understood the root of the speculation was that "the press got hold of a draft copy of the invitees and I missed the final cut; that's the explanation I've been offered".
"That's the way it is, obviously there's only so many that can go," said Dalton.
"He's an amazing world leader, it would have been lovely to have met him, or to have been in his presence, but it's not to be."
Tomorrow night he will be attending a mayoral conference in Wellington.
A spokeswoman for Local Government New Zealand said LGNZ had not had any involvement with arranging mayors for this event, and she was unaware of any formal communication from LGNZ about the event.
Event organisers the United States New Zealand Council did not return requests for comment.
An extensive media ban covers the event, and those attending have been told not to share the occasion on social media. Although allowed to confirm they have been invited, guests have been advised to decline interviews.