I just opened a bag of sencha that I was given as a gift 2 years ago. The can has been stored in a cool place the entire time (a fridge for almost the last 12 mos). The bag inside the can was vacuum packed so there was no air in the bag. I don't know what this sencha tasted like before so I don't know how it has changed if at all. It does seem perhaps a bit smoother and maybe "weaker" in some sense. However it doesn't have any of the unique flavors I experienced with Hibiki-an's kuradashi gyokuro.
Does anyone have experience with purposely or accidently aged sencha? Does anyone know how it should be aged? I know this isn't done very often but I have heard of it.