Why would he follow his ex on instagram if he wants me?

This guy who I'm currently talking to has just started following his ex on insta today. He says I'm the one he wants to be with etc. He asked me on a date 2 days ago so he's clearly interested in taking things further. But today, I noticed that he's following his ex on insta. I find this odd if he's pursuing me. Is he doing it to make me jealous or something. I just find this behaviour strange. What's ur opinion on this?

Why would he follow his ex on instagram if he wants me?
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