Where I am from that is not unusual. I call others Sweety all the time. My boyfriend calls most women Babe or Baby, not just me, from birth to old, it doesn't matter to him. She could be 100 years old. That's just the way we are around here.
They are trying to disrespect you. As a matter of fact, if they don't call you that, and they do everyone else, they don't like you at all! Just roll with it, change how you look at it in comparison to how it is around there. If they are from the south, they are likely to be like that with all ladies.
Personally, I kinda like it, because that means that there is a personal touch to how I am with them and they are responding to it. In my opinion, anyway!

Most of the time, 99%, it's not meant to be taken as flirting. I don't when I call someone Sweety. That's just my word. Sometimes I say honey or darlin'.

I call people: hun, hunny, sweetie, darlin', love, babes.. They are terms of endearment for friends and those I think kindly of... I don't use them to flirt in any way... Especially on here we don't always use each other's names and if you think well of someone you may not want to call them by their screen name all the time...

Honestly, what would you rather they call you? I've been called a lot worse by people who meant it...lol.

To have someone refer to me as "Sugar," "Sweetie," "Babe," etc. has never offended me unless they use a leering tone while saying it. And, I will politely tell them where my boundaries are.

If you feel it is offensive, tell the person who used the term. Teach them where your boundaries are. If you don't, how else will they know?