One hive in the yard is bearding halfway up the front of its lower deep box. Supers were taken off 7 days ago and it has a deep, med. and med. for brood. I even put 3 frames of foundation only in the top deep when I harvested honey so they would have something to do. Shall I replace foundation with drawn comb so they can simply fill them with fall honey? Why might this one hive be bearding and should it concern me(only mid 70s today)? This hive has no history of bearding over the past summer.