How does the author use foreshadowing in Casino Royale?

In Chapter 22, Vesper beings to act suspiciously. She is afraid about a seemingly innocent car following her when she is with Bond. Although, she realizes Le Chiffre is dead and they are out of danger, she still suffers from real fear. Bond seems to settle her down, but Vesper continues to act suspiciously..... foreshadowing a secret she isn't willing to share.