My friend helped me set me up with her manager for a job interview, and I got the job!
I got a job where my friend and my ex boyfriend works. My ex already knows about this because one of his best friends told him that I got hired but he doesn't seem to have a problem with it.

And so every time at work, he always looks at me every time we passed by each other. The other day, he was running in the hallway because he was in a rush but when he saw me he was looking at me for more than a second while running. And after that, he tripped lol. And my other friend told me saying "hey look at him." when I turned to look, he was looking at me.

So what do you think does this all mean? And also, He broke up with me 9 months ago but remain friends after the break up and two months ago, I started ignoring him until now. And do you think I should talk to him? In a friendly way?

It sounds like he might still have some feelings for you.

What you didn't know he worked there?

Got to prepare for that. You knew you were going to see him.

If he's an ex, then it shouldn't matter. Let him stare all he wants.
Do your job. Take the higher road.

Why are you there?

After a few times, it won't even phase you.
Get used to it.

People look, so what?
Ex, right? As in no longer...

As a male I would say he still has feelings for you I have even notied I'm staring at my ex in college talk to him and just see from there really