SHOULD I CALL MY PRINCIPAL LARRY?

Submit to the governing authorities.  For all authority comes from God, and those in positions of authority have been placed there by God.  So anyone who rebels against authority is rebelling agains thwat God has instituted, and they will be punished. - Romans 13:1-2

     I would always call my old principal Mr. Hartman.  Even after we would meet every Friday to discuss life at a local bagel shop, even after our families hung out together to make gingerbread houses, even after he drove to my house and we hung outside talking about our roles as parents and husbands.  To this day it feels weird to refer to him as Tom.
    He is my friend, but he was also my boss.  There was a certain amount of respect I thought he deserved as my boss and so I would call him by his last name.  And for the most part, I do feel like I honored that relationship.  There were times that I questioned his decisions in a respectful way, but I "bought in" to his role as a leader.
    Now I am older and "wiser."  I've started calling people by their first names - parents from my school, staff (I didn't even use to do that at my old school), and sometimes even.....my principal.  That still seems weird, but I do it.  As I'm typing this, I don't like it.  Call me old fashion, but I think your boss should be called by their last name.  I think it shows respect. 
     Thoughts?