I was taught to address my elders by Mr or Mrs but that is getting harder to do as I grow elder (sic.) myself. I mean, when I was 12, a fifty year old would be called Mr or Mrs but now, a fifty year old is only ten years older than me. . At this stage, I've noticed I have a twenty-year span to the Mr or Mrs use.

I do use Mr when being first introduced to someone of note (eg. the president of a company) then switch to first name basis as appropriate.

As to myself...
I don't usually bristle when somebody who I've been introduced to calls me by my first name. I do bristle if some sales person who I don't know calls me on the phone and does so. Mind you, I bristle at any call from a sales person. Oh well, never mind