My kids still call people they knew as little kids Mr. Ronnie and Ms. Debbie, etc. My best friend and I have taught VBS together for years and half the time I call her Ms. Bobbie out of habit, even among other adults.
As a young mom I was a teacher's aide at the elementary school. One of the teachers had been my 6th grade PE teacher and it took me nearly half the year to bring myself to call her Ina Mary instead of Mrs. Fossett. It just didn't feel right! But she said I made her feel old, so I tried really hard...