Thanks everyone. It was difficult to bring it up to her...but I mentioned it today. I told her I was concerned she is too tired, that she may not be listening to me and maybe I had done something to bore her? She was surprised and did not realize she had been yawning. She reassured me she was listening to me and that it was no way my fault. She did admit that she is tired but she shouldn't be as tired in the future since graduation is over. She took it well. She said she was glad I told her. Relieved!