It could mean a few things, but considering it was on overheard conversation between your father and your grandmother, I'm going to guess that it wasn't meant in psychological terms. I'm also going to guess that you haven't asked them what they meant? I'm leaning towards needing to be in control? What was the rest of the context? What brought out this conversation between them? I think it's important to bring up the topic with them so that you can reflect on how your personality and/or behaviors affects others or is causing them to talk. If they are even approachable?
I find it curious that this was a year ago and that it has festered in a way of replaying.