Ethical Dilemma #1: September

You are a counselor in private practice and you have a new intake scheduled for the day. The client, Sam Thomas, age 28, calls and makes an appointment for anxiety and a potential panic disorder. His name does not sound familiar.  He comes in for his appointment and he does not look familiar. After some talking about his history your realize that he went to the same High School as you and that he was friends with your younger sister in High School.  You are unsure how much contact they currently have.

What are the potential ethical dilemmas in this scenario if any?

If a dilemma exists, how do you handle it? 

Are there any ACA ethical codes being violated here?  Explain why or why not.