What advice can you give me on how to handle a situation like this?

So a younger guy that I work with, I believe he said he’s 21-22, keeps saying the same insulting thing to me but I keep brushing it off. I’m 27. I have been told I look younger, I have been told I look my age and maybe older depending on what I have on and how my hair is done etc but this guy has asked me twice how old I was and the first time he said “Dang. You’re 27. I thought you were 30 something.” I brushed it off, his opinion no big deal. A week later, I was on my phone and he says “Do you have social media? Old people Don’t usually get on social media like that. How old did you say you were? 37?” Once again insulting me, but I politely corrected him and left it alone then he proceeded to ask for my social media but it’s weirding me out that he keeps on putting that same insult out there and I can’t put my finger on what his motive truly is. It’s okay to have a opinion and think I look older than what I am and the same if you think I look younger than what I am but to keep saying it is where it’s becoming kind of disrespectful.

What advice can you give me on how to handle a situation like this?
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