Thanks for your input. Using the information you gave me, I went back and realized that a different gift I had received from the same person had a similar date, only with more information. It said, very literally, (in kanji) "Showa 55 year 7 month 29 day". This was a Dong Ding oolong from Taiwan. I looked again at the other one and it was "55.6.-3", so I had the date slightly wrong. Bottom line is that these indeed look to be from 1981. I opened up the Dong Ding and, while I don't have much experience drinking older oolongs, the leaves looked to be old. The canister was sealed and inside was a thin plastic bag with the tea in it--the bag looked a bit old, and it had a small piece of yellowed clear tape on top that looked to have deteriorated glue. I brewed five or so grams in my little yixing pot after rinsing the leaves twice. The brew is pretty dark and there is definitely an older taste that I recognize from the one other aged oolong I've ever drank. The difference was that this one was much smoother and had a hint of a very nice aftertaste in the first few brewings. There wasn't a strong flavor in any case, although the brew remained dark. The wet leaves were pretty small and uniformly reddish looking. They were not strongly crinkled like I've seen in some of the highly roasted oolongs I've had, and there were no black leaves. Overall, a very interesting experience. I look forward to trying more and eventually making my way to the Tie Guan Yin. If anyone has thoughts they'd like to share on storage or tasting of aged oolong, I'd be happy to hear them.