Should I dm this guy that followed me back? He graduated last year from my high school and I don't know if he's single?

I had a small crush on this senior last year and he's really cute but I didn't know him at all. I was bored yesterday and just decided to try following him on insta (his account is public) and he followed me back in like 20min!! I have a private account so I didn't think he would even request to follow me but he did! Because he did that I think he might be single but I'm not sure and I feel like dming him might be too forward? Should I just send him "hey" or is that too awkward? He knows I go to his old high school so is that just why he followed me back?

Should I dm this guy that followed me back? He graduated last year from my high school and I don't know if he's single?
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