Yesterday I noticed little yellow balls on the ground in front of one of my hives. I squished one of the balls between my fingers and i was mostly powdery. It looks like pollen. Today there are alot of the little balls in front of both of my hives. It looks like the pollen that the foragers are bringing in, but it also looks like the bees are actively throwing the pollen out of the hives. They look very intent on throwing the pollen out. Why would the bees do this? Is this something to be concerned about?