I store my whites in a double-lidded tin and they keep wonderfully. How airtight is the thing you're keeping it in? I wouldn't go any lower than a double-lidded tin. If you're currently storing in zip-bags, or single-lid tins that don't close tight enough, then you may be letting too much air get to them. Also, whenever you open any container, you let an amount of air into the container that is harmful to the tea. Your tea could go stale quickly if you find yourself smelling your tea a little too often... (we're all guilty of it
Fbones, moisture is harmful to tea. Moisture in the air condenses onto cold surfaces. It's OK to store your teas in the fridge, but you have to make sure whatever they're in is airtight, or else when you take it out, the moisture from the air around will condense onto the leaves. After taking a tea out of the fridge, you have to allow a fair few hours for the temperature of the tea to equilibrate with the temperature of the air around. It's really only recommended to store unopened teas in the fridge.