Debbie, the first time I had it for months. It was so depressing, they even put me in a soft cast. I was lucky this time. I think I was so determined to run this 10K (which I did this morning, pain free), that I healed! And yes, I do get twinges which worry me.
You may want to check out Dr. Philip Maffetone's book, The Maffetone Method. He talks a lot about injury in there. I bought his book during my last bout of PF and followed his advice when I resumed training. I realized what was causing my PF: not enough of a warm-up. I would literally sprint out the door. Now I go at a very slow pace for the first 12 minutes or so. Sounds obvious, but warming-up and cooling down really do prevent injury.