Screen BB acts as pollen trap?

[Hivehead]

Seems like a lot of pollen balls are dropping straight off the bees when they walk on the screen.  Problem? :? are they just clumsy and dropping it?  it's one of the two.
should I take any action?
Thanx in advance

[Moonshae]

They drop a lot. But picking out the pollen from the wax flakes, bee legs, mites, etc is probably more trouble than it is worth.