Something you don't hear everyday

I heard a term yesterday that I no longer thought was used anywhere but in novels taking place in earlier days:
Maiden Aunts.

I immediately wondered if they were "maiden" in the true sense of the word. At the age of 70 at the turn of the 21st century...? Is that possible?
Then, for me, they became Miss Marples in my head- Sharp, kindly old ladies who knit and are wise in the ways of human nature.
Maybe we need more maidens.