I met briefly with a professor last year and showed him a poster of my work which was not good at that time (It was some sort of a presentation in which we show our work and research). Then I decided to apply for a PhD so I emailed him and he told me to apply. I knew that he will be coming to the same presentation this year so I emailed him again saying that might be an opportunity to talk in person. He never returned my email. That was two months ago. Ten days ago I was rejected from that university (I guess he made the decision). Yesterday, I presented my work in front of the whole audience which was much better than the one I presented last year (Even though I was rejected, I tried to impress him). I didn't talk to him directly then. Just now he viewed my profile on linkedin (Which he did multiple times previously awhile back).
Does it make sense to follow up now? At to least know why I was rejected and why the sudden interest just after my presentation? I know it is very difficult, but would it even be possible to flip the rejection into admission now if he decided to?