I have the same problem. I live in a place where humidity maybe reaches 25% outdoors. I've overdried my buds before too. Like mentioned above, put them on top of each other in a paper bag for a day or so. Next time i'd use a humidifier in your house so that they wont dry out as quick... what exact percentage i'm still trying to find...
and to + rep people click on the justice scale looking like thingy on the top-right of someones post.