Chewing on her cud

Many times throughout the day I get the privilege of nursing my precious little girl. From my position I get a great view of her tiny face and simply gaze at her beauty. I often see her lying still with her eyes shut and chewing her little mouth like a cow chews on its cud....it is strange and I am not quit sure what she is doing. I have see other babies doing this too. Maybe she is sucking on her tongue or gnawing on her lips. Whatever it is, she looks too cute and love her the same!