More Personal Identity in Hip Hop

In this track, Dessa describes an experience where she had a hard time recognizing her friend as the person that she had always known him to be.  She struggles with the question of whether the person she interacts with is the same person who has been her friend for years.  When she questions whether she is really speaking with "The Man I Knew", what kind of changes make her question his identity?  What does this indicate about what she thinks are criteria for personal identity?