Thw wine is Au Bon Climat Le Bouge D' a Cote, Santa Barbara, Bien Nacido Vineyard, Chardonnay 1993. It had a good fill and cork and had been properly stored since release.
I have reported on this and other reserve Au Bon Climat Chardonnays here before. Without exception, they have all held well over 10 years and in fact need several years to show well This wine is likely at the peak, but it would not surprise me if it holds well until it is 20 or more years old. It is the closest California I have found to top white Burgundy, and has much in common with it, especially when well aged. It perhaps has more of a grapefruit citrus character than white Burgundy, especially when young and not mature. I have tasted top California Chardonnay from other regions and producers in some years, but not in other years. This and the other reserves from Au Bon Climat, at least from the late 80s and early 90s, really have nearly no competition for quality in California if one averages over several years. The wine could easily pass for 15 years younger if I offered it to those who drink the huge California Chardonnays that often are impressive early on, but start down hill nearly as soon as they are in the bottle. IMO, a reserve Au Bon Climate should not be opened until it is at least 10 years old. The problem is that production of the regular Au Bon Climat is very small, and that of their reserves is extremely small. Although you can easily pay more for Chardonnay in California, the Au Bon Climat reserve Chardonnays are not cheap. However the main problem is finding any at all to buy, even in California.
Au Bon Climate can not exist on reserves only no more than a top German estate can exist on TBA only. Their regular Chardonnay often is several steps down from their best reserves. They also make other types of wines ranging from "me too" to outstanding quality.