Words to live by: Never buy just one bottle - for a number of reasons. I would recommend, when you are wine shopping, if it's possible, buy at least two bottles of the wine that you are interested in. How disappointing would it be if you had been cellaring a much anticipated bottle of wine, only to finally open it and find it was, say, corked.
I generally buy two bottles, but especially when I am curious as to how a particular wine will age. Of course, that doesn't mean I go around everyday buying bottles of Pétrus by the brace, I don't have that type of wine-buying budget, but when I come across an affordable wine, which I think has potential of some sort, I more often than not buy multiple bottles.
In the case of this Madrigal 2005 Zinfandel Vinomaker and I bought a dozen. We have liked Madrigal's Zin for a number of years now and with an inter-winery discount it was very affordable by the case. Just as well, because the first bottle we opened last night was indeed corked - a nasty, musty affair - so we opened a second and it was delightful (even if it is getting a little long in the tooth).
Think of it this way, purchasing two bottles of the same wine at a time is insurance against disappointment.