Sometimes a load that is too hot can blow the skirt. A crimp that is too hard can make the plating drag.
Though what you describe sounds like a squib that was popped out by the following round to a T. Check your barrel to assure that there are no bulges. Most times if it happened with a light load it will not hur the gun.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.