End Scene...
+1 cortez
The key truly is to forget about it. Tampering with your aged blends is never a good idea until you are ready to smoke them.
By the way, the original tin is preferable to a mason jar as long as the seal is not compromised.
(Bulks will obviously require the use of a mason jar)
Small rectangular tins like Penzance or the "Lakeland" tins like Sam Gawith are fairly vulnerable, but if you can't open the tin by applying slight pressure with your hands or if you can't smell anything they may be okay. C&D/McClelland/round European tins are fairly reliable. Use your judgement and if you think they are at risk, then jar them up.
Supposedly every tin you open a tin/jar, the microbiological processes that affect aging are restarted at best and completely ended at worst.