Not too long ago, being called “ma’am” (which usually happens in a service-type situation, with a waiter or cashier or what have you) made me feel kind of Grandma-ish. Like I am no longer a vital (nudge nudge) woman in the prime of life.
But lately, I’ve decided I like “ma’am” better.
After all, if you’re a military officer, you start getting called “ma’am” even if you’re fresh out of college and all of 22. And “ma’am” is common in the South, I’m told.
Also, I’ve observed that those who call me “ma’am” are generally more attentive to their jobs.
I like to think they look at me and observe, “I totally respect this powerful lady. I better not trifle with her, or I will perish! Also, I want her to have the very best experience at my company that I can provide, as I take full pride in my position.”
Perhaps I’m assigning it more meaning than it’s worth.
Anyway, I’m starting to find it slightly annoying to be called “Miss.”
I want respect!
And if it makes you feel kind of old, well, just pretend you’re a dominatrix and you want them to call you ma’am.
MARGARET DILLOWAY 
Awesome post. It is said that Elvis Presley was taught to call anyone one year or older ma’am and sir. Being from Texas it was mandatory. I came to the same epiphany you had while in my mid-20’s (married w/a child). I find that I also respond better to those who call me ma’am. Sort of a full circle respect thing!
I was first Ma’amed in my twenties on a Southern playground. A child who did not know me wanted my attention. It was kind of weird, but it worked. My southern husband has failed to convince my children to use the term. Now I hear it most from people who are clearly older than I am, which seems awkward. But I guess they’re the ones who know how to be polite.