I keep my primed 9mm in a big tupperware type container with a desiccant. When I open it to add brass or reload some, I chuck the desiccant in the oven on low to "recharge it", then seal it back in when I'm done...
The problem with ziplocks (or any sealed container) isn't moisture getting added, obviously that doesn't happen, the issue is if you have wide temperature swings, and other conditions are just right, what moisture that's in there can condense into water before being reabsorbed into the air.... When its in its water state, it can tarnish stuff, and, perhaps damage the primer.... But, it the area they are stored is temperature stable, you will be fine.