Dropping The Misses and Mister

I bumped into one of my high school teachers at Target, and my instincts immediately took over when I said, "Oh, hello Miss Laskey."

"Miss Laskey?!?" she replies.  "You know you're old enough to call me Rita, right?"

Later at a friend's birthday party, I struck up a conversation with my friend's dad.  "Hey, Mister Sullivan."

"Hi, Todd," he said.  "You know you can call me Ron, right?"

My answer to both questions is: "Yes, I know that I could, but I can't."

Despite being in my mid-30s, I automatically revert to being a teenager around former teachers or parents of my friends.  It just feels wrong to call my 10th grade Spanish teacher "Rita" even if 20 years ago that's what I called her behind her back.  As for my friends' parents...the words just sound disrespectful when they come out of my mouth.  They're always be "Mister or Misses So-And-So" to me.  While I'm perfectly fine continuing these formalities, it seems to bother them more than it bothers me.