How should a non-Muslim address an Imam?

I am not a Muslim, but I have visited a mosque before and enjoyed the service. When I visited, the local imam approached me and we talked a little about questions that I had regarding the service. I understand that imams have a very special position in the community. * Is there a special way to address an imam to show respect? * Also, is there a special way to talk about an imam with friends? I found [this question](http://answers.yahoo.com/question/index?qid=20100201213129AA6Y0RK) on Yahoo Answers particularly interesting, but the accepted answer seemed like a better fit for a first-time visitor. I'm hesitant to use Arabic phrases that a Muslim would use because I don't want to sound like I'm mocking him.