Opinion please on work situation...?

In my department there are 9 people...5 of us are in cubicles and the other 4 are in a office and normally keep the door open so that there is always open communication amongst us. Today, they door was closed to the office and we could hear them laughing. I feel like they were gossiping about us, How should I handle it? Oh, and the 4 in the office are of equal rank to us. They aren't supervisors or anything.