I wouldn't worry about it.
A lot of pull-down powders came in paper bags. It will be fine.I wouldn't worry about it.
A lot of powders used to come in cardboard canisters. They sure as heck weren't airtight. I kept them in a cabinet in my dry, but "relatively consistent temperature" basement for years, and I never had any of them go bad.
BTW - I loaded some .357 Magnums last night using Unique from a 25 year-old+ cardboard canister. They'll probably work just fine.
I remember my uncle going to the hardware store and they would shovel the powder from a big wooden barrel into a brown paper bag and charge him by weight. I think it was 4831 but I can't remember for sure. It sure was a different time especially since you could pick a Springfield 03 out of another barrel and pay only $15 with no paperwork.
