In "The Name Means Thunder," how does Paige's window screen end up playing an important role in the plot?

After Paige removes her screen so that she can escape out the window, Frick puts it in her closet because David's mother does not want him to replace it in the window in case Paige tries to come home that way. Later, when David is looking for a hiding place, the window screen falls and hits him, drawing his attention to the still-screenless window as a means of escape.