She doesn't want me to meet her baby daddy?

My girlfriend of 9 months and I just moved in together. She has a kid and things with the baby daddy don't seem very good. She says he was horrible to her and she had to move out. Thing is I walked in one day and she was talking to him and he was actually yelling at her telling her to not call him anymore. My girlfriend got mad and said it was just about the kid and then he said that she still calls every day and it was annoying him. He comes to get his kid on the weekends and she always wants me to stay in the house and out of sight. She also doesn't want me to talk to him when she will call him about issues with their kid. I just get the feeling she is almost hiding me. Is this an issue?
She doesn't want me to meet her baby daddy?
Post Opinion