Frames that fail catastrophically are almost always damaged substantially in the course of an accident. That looks to be about the size of a good thumb nail clipping an i don't think it is as deep as it is wide. There should be an abundance of metal that is structurally unaffected in the area and which experience relatively little stress (compared to about 2" closer). I wouldn't worry. I would keep an eye on it. After a while of not seeing anything change you'll tire of looking at it.