What you are hearing is probably what we call the egg song. Not all hens sing it when they lay an egg but some do. There are different opinions as to what it means. My thought is that the hen does not know where the flock is so she calls to them. When she calls my rooster might leave the flock and go get her, mating her when he finds her. I see it as nature's way of seeing that a hen laying eggs gets those eggs fertilized. Not all my roosters do that, not all my hens do that. I do not have to have a rooster for some of the hens to do that. Hopefully others will give their thoughts and opinions, some can be interesting.
I don't see that as panic or freaking out. She is simply asking "Where are you?" Whether any answer or not she will find them.