The ex still being in the picture?

I really don't think you have anything to worry about. Also you should talk to you're girlfriend about the ex and learn what their friendship is like and possibly talk about boundaries. As long as she hasn't given you any reason to doubt her or him crossing the line then you're just worrying to much. She's with you. And besides being friends with isn't a bad thing it shows you're human. But I personally believe that you should only have any contact with an ex is if you and the ex have children together that's it.

No it's not normal there is a saying that goes if a girl can still be friends with her ex after they broke up it means they never were in love or they still are. In your case I hope it's the first. I am not necessarily sure if its normal for a girl and a guy to be friends after a breakup perhaps it would be normal if they both decided that they were better off as friends I would personally find it offensive that she was still so close to him. Just because she is open about it and doesn't lie to you that she talks to him does not mean that it makes it any less comfortable for you to know about it. If it bothers you talk to her its the best way to get things out of the way.