Similar happened to me - twice.

A "Miss" at high school whom I had for 2 subjects = 10 periods a week AND as the school reps sports manager, was a teacher at my children's high school.  We still got along fine, when we met up at the school canteen window.

The other "Mrs M" had been the very strict Music Teacher and Girls' Supervisor at high school, that had a strict dress code.  You know, belt not too tight, hat brim d-o-w-n, hem length, etc .  Being a bit of a pushing-the-boundaries-type of schoolgirl, I had the odd occasion of friction.

Well blow me down, 30 years later she walks into the store......straight away I look down to see if my socks were folded down.  She recognized me too, then went on to say what good students my siblings were.  Yeah, yeah......

DEB