It probably attacked her, not save her, assuming it's real. I mean, there's no way a dog would know to do that if we just recently thought of it (right?).
I have a golden retriever. He is the smartest dog by far that I ever had. I don't think the dog knew to jump on the owners chest to save her life though. It's way more probable that he noticed her acting strange. Then when she fell he thought she wanted to play, and jumped on her. Golden retrieves love to play. I'll bet that mine would do the same thing if I started hitting my chest like she did and then lay on the floor.
I wonder if you laid there for long enough if it would try to eat you.