If it's picked up a bunch of humidity it's going to be heavier than it used to be - so a pound of humid malt is actually less grain than a pound of dry malt. You can adjust your recipes to account for it, I think 40 lbs is too much to dry in the oven but that's me.
Tom, that's a great point! Never occured to me.....
I was thinking of taking my container outside and leaving it in the sun (or in the shade in 90F heat) for a couple of hours. Bad idea?