I've previously had head separations in bottlenecked rifle cases. In the bottlenecked cases the causes were variously: headspace issues, improper annealing/hardness at manufacture, full length resizing too many times. Critically all of these caused head separation much closer to the case head than shown in your example. However I've never heard of it with straight walled cases. The only straight walled case splitting I've seen have been longitudinal in the body or neck.

If you know Jason Hornady it might be a good idea to keep the damaged case and the others from the batch. I suspect that any decent manufacturer would want to identify any metallurgic problems before they cause more serious issues.