It may be some food debris mixed with blood that came out. As shinty stated, a dry socket is usually quite painful and would need to be "packed" with placed with a dressing.
Don't worry, you WILL KNOW when you have a dry socket, they are very very painful indeed. It was probably a clot, but not the clot that is in the socket (up further) that would cause a dry socket. just keep on doing what you were told by your dentist, or oral surgeon and you will be fine. Good luck.