Why would he drive by my house?

Ex and I broke up after 4.5 yr relationship. No contact on day 9 , he lives over other side of town. He drove past and slowed down and beeped and waved and smiled. He took a long hard look in my yard too. I was sitting on porch. I don’t understand this. Why would he do this if he was the one that refused to work at it with me? He also has opened up a lot of his Facebook profile posts too- where as before he didn’t.
Updates
+1 y
An update ** conversation went as follows :

He: keeps referencing to time helping sorting everything out and using smiley faces.
Me: I responded with a non commitment type of text reminding him to get some sleep (in a light manner). The break up: is surrounding family dynamics and issues and boundaries , how it effects mental health and ability to focus on goals and aspirations and as couple. I trying hard to get my stuff sorted and he is very driven, he says I have potential.. still confusing
Why would he drive by my house?
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