I don't think you should keep your bud in an airtight container,
(especially if the pot still has a little bit of moisture in it)
Becuase there are anaerobic Bacteria that function in
the absence of oxygen and will attack your bud!
They digest Sugars and release ammonia as a waste product.
The bacteria will often(more likely with moister marijuana)
attack the weed,Turning it from green to brown as they digest the
Cloryphyll.They also destroy many of the terpenes/essential oils
-the odor molecules-leaving a musty ammonia-like aroma.
The marijuana will still be potent as these bacteria don't consume
the THC.

That said,
I believe THC deteriorates over time....but you'll get more CBD
My Stepdad had a coffe grinder that he never cleaned once!
when it the motor broke down he put it away and bought another one....anyways I grabbed the buster sometime later and there was
(my estimate of weight) about 2-3 grams of the most amber golden Kif I have ever seen!I Think it turned gold because it sat there for a good year or more.
I got Incredibly stoned off it though!