Hm, maybe a few basic guidelines as far as I've understood and experienced these things. I'll say before that these are rules of thumb and there are numerous exceptions for every one of them, but basically, you might say:
- Air exposure for maturation is only relevant for Pu-Erh. The other tea varieties should be stored without air contact.
I'm gonna be beaten up for this, but: Even for Pu there are some who think that it should also be stored without oxygen; e.g. Hojo
and the Tea Urchin
- You might say that most 'greenish' teas don't age well. That means most of the green teas, but also green style Oolongs.
- Everything that has more roast and/or oxidation will age better: Especially darker (traditionally made) Tie Guan Yins, Dan Cong and Yancha. (especially of DC there are also green varieties made now).
Many exceptions here too! E.g. many japanese greens neeed some time after production, the more deep-steamed, the more quickly they're ready.
But what I think might be the explanation for your case: Most Oolongs that have been roasted to a larger degree should have at least a couple of months to rest for the roasting aromas do disappear. The teas will not be so very pleasant before that has happened. Maybe you got a very freshly made one?