What does it mean when your ex boyfriend stares at you?

We dated for 5 months and we broke up. About 1 month later we started talking again and he asked me out twice. I said no an I guess I still liked him and I don't know why i said no. But all this happened in September. But yesterday I caught him starring about me and he quickly looked away. And sometimes he'll snapchat me and we'll comment on stuff on Instagram but idk. I sorta think he likes me and so does my friend but then again idk.