Once you have dried your bud it is ready to be cured. Once you are happy with the amount it has dried/cured then what? Mason jars are the best right?... But I find once I leave them in the jars after they have reached a good consistency they continue to get over dry.
It depends on alot of factors, but I have noticed this from time to time even in a humid environment. Depends on: Temperature/Humidity*** Size of mason jar/how full it is How often you open the jar ***Being the most important. If your in a dry/arid environment, then every time you open the jar your letting dry air into it. I would get a bunch of small, jam size mason jars and put them into a gallon zip lock bag, or a larger, sealable container. This will insure a double seal in case the jars are allowing a small amount of air inside. But a properly sealed mason jar should suffice. I'd say opening and closing too often is the case.
I always found that with a jar full of buds it'll keep better but as you get down to the bottom more air is exposed at the top, thus causing them to dry out quicker. Similar to what the user above me said, I believe you should get a smaller jar to keep as a smoking stash and let the other jars sit full.
Grab a boveda humidipak, 62%. Just throw in the pack into a jar, medium (8g) size will be fine for a quart jar. It will keep your herb at the perfect humidity level. They last half a year or so. The 62% one has been specifically made for marijuana/medicinal herb.