Sir and Ma'am

I grew up in the rural south. I went to a school in a farming area. Heck, I took some shop classes in high school, and after I got into them I loved them. (Oxy-acetylene cutting torch = feelings of empowerment.) I even belonged to the FFA. I was drafted for extemporaneous speech and parliamentary procedure because I could talk a blue mile, or as the shop teacher put it -- he "needed my mouth."

Another thing we were taught, both in shop class and in general 'Shire society, is to say sir and ma'am as a general rule and always to our elders. Not nessecarily every time a phrase exited our little mouths, but reasonably often within a conversation. It's stuck. I say sir and ma'am to anyone who might possibly be five minutes older than I am, and to almost anyone with whom I'm engaged in a formal interaction with. (e.g. Any cashier is a sir or ma'am. Even if he or she is probably younger than I am.) It's just a part of my scripted interaction with the world.

So, recently, I've noticed that folks are starting to react to sir or ma'am with a comment along the lines of -- What? You just called me sir? -- or -- Don't call me ma'am. I'm not that old. -- Not everyone I encounter, but a decent number of people seem to be mildly offended by sir or ma'am. Terms I view as the closest equivalent to the Russian вы or French vous in the English language. I've been informed reactions will grow increasingly hostile if I move up North.

So, sir and ma'am, have they somewhat shifted from a sign of formality and respect in language to something derogatory? It confuses my little shop class brain. Shall adherence to the rules of ma'am and sir go the way of avoidance of "barnyard" terms?