Hey, How's it goin' Mr. M.?

My son is a sophmore in high school this year. The same high school I attended some years back. A goodly number of years to be honest. A catholic boys private school run by the Brothers of the Holy Cross. The name of the school (sounds like Notre Dame, well ok, it is Notre Dame) is a popular name for that kind of school and there are many across America. It's almost like a chain (like Denny's or Walmart).
Anyway, last year when my entered as a freshman I realized there were many teachers still teaching there from when I muddled through. One of them seemed very, very, very old when I was there and he's still there and I'm thinking, "is this guy animatronic, or what?". And here's my point. Even though many years have passed betwixt me and my alma mater, I find I still can't bring myself to call teachers anything other than Mr. such and such, or Mrs. I hated your class. Why is that? At least one teacher I had was fresh out of college just beginning his career at the time he was molding my mind, so essentially, he was (and still is!) 7 to 8 years older than me, yet it is beyond me to say, "So Tom, how's it goin'" That would be just too weird. Why do we become kids in school again when we're around our former teachers. Since we are no longer in school and they no longer teach us, in fact they are part of our peer group. They have become people you can talk local politics with, or sports, or news stories, small talk, or just plain Grown Up Crap. But no not really because somwhere along the way we're always in school so we call them by there "teacher names".