do older spanish people get offended when you call them by "usted"?

so, i'm an immigrant but i speak fluent spanish (pero estoy escribiendo esto en inglés, para que otros extranjeros entiendan lo que digo). however, my spanish is VERY south american. therefore, i don't really say "tú" ever, i use "vos" for friends, and "usted" in formal situations, with complete strangers or with people significantly older than me.

i recently met the mother of one of my spanish friends and while i was talking to her, i used usted. and the minute i said that, she got upset and said "no me llames de usted!" and my friend had to explain to her that i don't speak spanish from spain and that's just how i talk, and that i wasn't trying to offend her.

is this a thing that commonly happens in spain? should i change how i talk?