I'd guess user error as well. Some months ago my brother I are were getting ready to shoot and I mentioned that I thought my sights were off. He had me shoot, then he shot. BIG difference. He watched me some more and then made a couple of small corrections to my hand positions and, darned, if those sights didn't go back to the way they were supposed to be. It had been a while since I had shot and the lesson is that no matter how good you might be at something if you don't do it regularly you lose your edge. Just keep shooting every chance you get.