Maybe Bernice is rewarding you for taking such good care of her. Or maybe Bernice isn't the layer and she just is the town crier and lets you know someone laid an egg . What the trick someone mentioned on BYC to put lipstick vent vent and see if the next egg is marked with it. I wouldn't use a bright egg or the chickens might attack her. I would also let Bernice keep the tube of lipstick.