Today I went out to collect my single egg from the only chicken pulling her weight around here. She was sitting in the nesting box, and I could see that the egg was already there. But she was sitting there, and her vent was pulsating a little, almost like she was going to lay another one. She sat quietly for about 2 minutes, and then started singing the egg song, loudly. Kept it up as she stood up and walked out of the hen house. I thought they only made the noise as they were actually laying the egg?