Airtran did that to me a couple of times while connecting in ATL. I remember that I had to RUN in order to catch my connecting flight, because it was in another concourse.
As you are coming in for a landing ask the flight attendant which gate you will be arriving at. If she says that she doesn't know ask her to ask the pilot. Then compare with whatever gate you have to get to. That will at least let you mentally prepare yourself as to whether or not you have to run to another concourse. Hopefully, not.