AIO for telling my coworker to stop calling me “sweetheart” at work even though he’s twice my age?

I (25F) work at a small office where everyone’s pretty casual. There’s one older coworker (mid-50s M) who’s generally nice but constantly calls me “sweetheart,” “kiddo,” or “hun.”

It started off as something I brushed off because I didn’t want to make things weird, but it’s been months, and it happens every day. Stuff like, “Hey sweetheart, can you print that for me?” or “Kiddo, you’re too young to stress like that.”

I finally told him, kindly, that I’d prefer if he just used my name. He laughed and said, “Wow, touchy much?” and told another coworker that “you can’t say anything to young people these days without offending them.”

Now everyone’s acting like I made a mountain out of a molehill. My manager said it’s “not worth HR drama” since he’s “harmless.”

I feel like I’m being made out to be some kind of diva for just asking for basic respect.

Am I overreacting for being upset about this?