In the past couple weeks I've had at least 8 light bulbs burn out. Two of them are 3-way lamp bulbs and only the middle range will light now. The rest of the bulbs are in fixtures that are in the cold. Two inside the garage and the others in exterior wall sconces. All are incandescent. Should I be worrying about an electrical problem somewhere in my house? Or perhaps, is it just dumb luck that these bulbs are all old enough to give up at the same time?