Last night I noticed one of my chicks was acting extra lethargic. I had just got her 2 days before. My husband thought it was just exhausted so we let her sleep. This morning I went in to check on them (7 chicks altogether) and she was dead with the others on her. I thought maybe they saw she wasn't doing well and were trying to keep her warm. My husband thinks maybe they suffocated her because she was dying. Any thoughts to why they would sit on her? Should I worry that they may end up like her?