It must be because her memory has been altered that she kept having such nostalgic feelings at the moment. At the same time, she was having a hard time distinguishing her feelings.
Elizabeth has these mixed feelings of happiness and confusion. She was pleased to be right about the symbol but confused as to why seeing makes her feel uneasy. Yes, the symbol she saw was indeed the sign in her memory that will lead to the secret pathway but how come she doesn't see any clues as to where the door may be. No matter how hard she tried to think about it, she couldn't recall at all nor remember what the door looked like.
"It can't be. I was sure this was the right symbol."
