Answer the question about text:

Sometimes I called myself , but not often enough . Mary would always say , " Let me get Bob , he will be so pleased that you have called . " The last time I called , within the past year , Bob knew who I was , but could not remember any of the facts he used to so quickly retrieve from his mental archive . We still had a very pleasant conversation , after which he said , " I have to write a note for Mary while you are on the phone to tell her you called .

Why is the narrator surprised by Bob ?
Their mind is going .