Sorry about your loss, Fitchie. I know how sad that is. One day they are fine and the next, they're gone!
There is really no way to know if what your chicken died of was an infectious disease or something else without taking her to a veterinarian for a postmortem exam. I can tell you that this exact thing happened to one of my chickens and I was able to do an exam on her. She had something called fatty liver hemorrhagic syndrome. It is extremely common in laying hens, particularly the good producers. Their liver gets very fatty and as a result, very fragile. The liver breaks, they hemorrhage. As a result, I quit feeding my chickens fatty leftovers and have not lost any more.
This is not contagious and is only one of the more common possibilities to explain why your chicken died.