The person who has my old phone number texted my dad something weird

So a couple years ago I had changed my phone number. Due to having the same phone number since high school, not wanting certain people to contact me anymore, having fall outs with people, an ex who still would reach out to me periodically, and just wanting a fresh start. So all of my immediate family have my new contact number in their phone. But last night my dad received a text that just said “you’re popular” at 9:00 at night. Which he ignored and blocked, because he knows it was not me. He wasn’t interested in replying or calling them to ask about it. It was strange because I have no idea how the person with my old number would ever have my dad’s number, or even know his name to search it up, or why. My only thought was maybe this person wanted to contact me, but couldn’t find anything, so searched for my family’s numbers on Google? If they are tired of receiving texts about me, it’s just a weird way to handle it. It’s all just odd to me, and has made me feel somewhat uncomfortable all day. It also made me think that maybe whoever is texting my old number, could be someone who I’m not on good terms with, and is saying things about my dad for some reason. I have an overactive imagination and just want to feel safe. Any advice or ideas, from an outside perspective?