I didn't know there was one in there. The Grey Ghost/Nightcap mixture I got from a guy who sent me a package similar to the one I sent you. It was in a plastic bag and I just dumped it all in the jar.
I wouldn't worry about the humidity with the mason jars. They are pretty air tight and the humidity souldn't escape. They will keep for years.
This is from Greg Pease:
Q: What's the best way to store tobacco for aging?
A: Ideally, tobacco should be left in its original sealed tin, and stored in a cool, dry place. It's important to realize that storage in plastic bags and the like, while allowing the tobacco to "meld," will prevent the true aging process. Plastic bags are permeable to small molecules. (Water, while not a very large molecule, is polarized, and has a hard time penetrating the barrier formed by the plastic.) If you can smell the contents through the bag, you're losing flavor and aroma! Mason jars, bail-top jars and so on are good candidates for long term storage, as long as you can resist the urge to open them to "check up" on what's happening. Aging tobacco must be left alone, with no gas exchange allowed. Once an aged tin is open, the contents should either be smoked relatively quickly, or transferred to a jar with a good seal.
Sam