I just purchased a pack of Rage 2-blade after reading the rave reviews. I've always used a fixed head up to this point. I understand the Rage heads lock in place with the o-ring. I can feel that them lock into place but they still seem very easy to open...almost too easy. Should I be worried about the blade deploying in air??? I hear of some folks using rubber bands just in case...but I can't find the orthodontic type bands that small.