I was just locking them up, when I heard one of my chicken squawk. It was much lower than normal. Does she have enough water?
Chickens make a lot of noises, so if there is always water in the coop, you should be fine. If you are concerned, you can watch them to see if the others are keeping her from the water. If you have a lot of birds, but only one water, i would add another one.
My chickens make a lot of noises including one that sounds like a dog barking. I don't worry about it, but the cat looks at them funny when they do it.