Rogergendron, sorry to hear that problem, but lucky your OK!
I was thinking about coaster brakes doing that recently. I friend of mine got a bike and it would lock up occasionally. He used it hard though. I looked and saw that at one time the clamp that holds the arm for the hub came loose. That I told him was causing the problem. But after that was fixed by getting the clamp bolt back in place it still had problems. Some times he would pedal and it would just slip.
For myself I just know if you don't have hand brakes, at least one as well as the coaster brake, what happens if the chain falls off and you going down a big hill. It happened to me.
page 1 post 5 I replied to this thread about that experience.
Getting rid of coaster brake all together, I can say I did just a bit more (no pedal crank), but it is not legal on roads, only off road in motor cycle parks or private land. It was a bicycle but now it is classified special motor cycle by DMV.