I fear this "meeting" is an omen of things yet to come. How can I protect my personnel file and future evaluations?

Veteran teacher of 10+ years. New principal summoned me to his office and voiced "concerns" about his "feeling" that I was unhappy and did not want to be there (the school), and that I cared ONLY about academics. I was shocked, no harsh words, etc. Have only known him about 6 weeks. Did not ask for specifics (knew I should have, but too stunned). Is there any type of formal affidavit/declaration that I can make to place in my personnel file. I genuinely felt like he was trying to establish grounds for something that will later affect rating on evaluations (participation in non-academic activities is one section of evaluation).
Have to return tomorrow and feel need to clarify/correct in writing and place in personnel file so that if/when I receive bad evaluation, it will be obvious why. - Is this your question? Add additional information