I found one of my hens dead in the yard this morning. (I have a coop with a secure attached yard so I can leave the pop up door open without threat of predator. The coop has a heat lamp so it is warm enough, there was plenty of fid and water.) She looked like she had just lay down and died, with no apparent injury. She seemed fine yesterday. None of my other 10 chickens are showing any signs of injury or illness. Should I examine her body to see if it was egg binding or some other physical issue? This is my first year as a chicken owner -- just since last spring. All 6 of my brown egg layers laid an egg yesterday, so she was fine then. What should i be looking for?