well, the circumstances before she went broody may have helped her along...I ran out of feed four days ago, so for three days, my girls free ranged. There is plenty of forage in the yard. I had four ceramic eggs clustered in the nestbox that stayed there day in and day out, all in the favorite spot, so every day there were up to seven eggs in that box, and that may have trggered her to set.
I think the combination of the predator attack and the removal of the eggs broke her out of being broody though. She was in the nest last night, but not this morning. She hasn't been back in the nest today. Oh well, good to know that she will go broody for me for the future!