It's not usually a concern, unless there are other contributing factors. How the scar healed, if you have issues with your uterus, etc. If you had a straight forward delivery and healing, I don't see why it would be unsafe for you, but you should ask a Dr. to be sure.
What kind of incision did you have? I had a horizontal one below my bikini line. It's barely there now. My sister had the vertical one that goes from her belly button down. Apparently, there are bigger risks with that kind of incision, but I'm not sure what they are. Other then her stomach muscles being shot, the Dr. made no mention of not having another baby that way.