I'd heard that a newly hatched queen will pipe and any other queens still in their cell will answer. She then proceeds to kill the other queens. She may have just been testing to make sure she was the only queen. Kinda neat you heard her. I like to listen to the hive. sounds like a purr almost. would make a great "go to sleep" sound if my wife wouldnt complain that it makes her feel like she has bugs crawling on her!! LOL