@ladyinpink,
When he asked you "Where were you at around 6?" you could have asked "Why do you inquire about my whereabouts?"
When he asked, "Who are yu talking t on the phone?" you could have answered, again, with a question, "Why do you want to know?"
And, "Do I look old?" you could have asked, "Why ask me? Do you think you look old?"
Throw the ball back in his court! Fish around, ask yourself, "Is this man a nut, or is he just lonely, lost, stupid, or merely trying to start a conversation?