Normal Behavior In A Three Year Old

I recently had a lovely couple stay here with their three year old daughter. It has been pretty chilly, down to the 60's and the child was playing in the dirt with nothing on but a diaper. She was barefooted and I was concerned because she was playing beneath a lot of rose bushes. Then, upon my verbal concern, the parents said, oh, we always know where she is. We can tell by her cry of annoyed or concerned. Then the father goes and picks her up. The little girl had gotten into the swimming pool which was cold.

This little girl will not look directly at you, ignores any kind of response to talking to her. Even today when they left, she turns away and will not speak to you. I have never seen a child like that.

What are the symptoms of bipolar disorder? Something seems very wrong here but I do not know what to do. They are very loving parents and treasure this little girl. She is theirs not mine. The mother said that her own mother used to worry about every little thing and was overprotective. Maybe this is her way of not putting that trip onto her own child. I don't know. It worried me.

Does anybody have any advise as to what could be the cause of her behavior?

They also had her in a public park yesterday, again barefooted. I would be so afraid she would hurt her feet. I touched her feet and they were really cold.

Thanks.