What legal rights do grandparents have in pennsylvania?

My ex boyfriend and I have a 2 year old daughter. Throughout our 3 and a half year relationship my exes mom usually took my daughter about once a week to spend time with her. She really is a great woman and I trust her caring for my daughter. Since my ex and I split about a month ago, she still continues to take my daughter about once a week. I never gave her a problem about this as it is absolutely no problem with me. Recently, I was informed that she had gone to a lawyer and had him write something up to secure her visitation rights with my daughter. Although, she is a great person in the sense of being caring she also is very pushy in getting what she wants. I feel threatened because I have not given her reason to believe that I wouldn't let her visit with my daughter. I could see if since my ex and I split I had yet to let her see my daughter but that is not the case at all. I am not saying that it would be anytime soon but years from now after I'm done with school, I don't necessarily want to be tied down to the area i'm in. I very well may never leave but i'd like to have the option open. Is there anything that a grandparent could do to legally tie me down to the area i'm living in? This isn't an issue with the father of my child. I understand that if he really wanted to he would have the right to have me stay in the area to assure he sees his child. That isn't the case though. This is purely the grandmothers doing.