Do I have to sign a confidentiality agreement from my previous employer after leaving on good terms and giving 2 weeks notice?

I worked for a private company as Sales & Marketing Coordinator for 3.5 years. I never was asked to sign a confidentiality agreement in my entire employment. I have always worked in good standing, with integrity, professionalism, and held things in confidence concerning all confidential matters. In seeking another job opportunity with better pay and opportunity to grow, I was contacted by a recruiter and landed a job with another company in the same city as Executive Assistant to the owner. Both companies are in the same industry - real estate development - so some might say they are competitors, although the sales & marketing staff of both companies have a good, positive, friendly relationship. In giving my notice, I was transparent as to where I would be going and what position I would be taking. My boss congratulated me, as did the owner. Two days prior to my last day, I was handed a 3-page confidentiality/non-disclosure agreement my current owner wants me to sign. Must I?