Is it normal that i'm being watched?

I have an ex from years ago that seems to know where I'll be. We live near each other and once he told me (after we stopped talking) that he saw me in my uber which kind of creeped me out. But I'll notice I'll "run" into him a lot. One time I was running in the neighborhood and he passed by me on a bike and waited for me to run up to him and I just passed him because I didn't wanna talk. When I say "waited" I mean stood there looking at me until I ran pass. Another time I was coming from the pizza store two blocks away and he was speed walking up my block toward me and I ducked away into my house before he could reach me. This stuff happens every now and then and I'm wondering how it's possible that he seems to know when I'm outside? Am I overthinking it?

I feel like someone is telling him where I am or that my phone is tracked but people don't seem to believe me.