Question about servers.

On the server browser there are different Icons on the server. Theres a Lock with a circle around it (which probably means its passworded), a server icon with a small lock in the bottom corner, and just a server icon. Before I signed up for the free month of Gold, I tried to join a server with a server icon with the small lock in the corner. It said that I need Gold service to play in this server??? I thought all servers on server browser are free :confused2: . Once i got gold i could join the server.

http://img295.imageshack.us/img295/7982/serversjj2.png