Blue ox pin failure

We were on the road in Mexico. I have been using a Blue Ox tow bar for over 10 years. This was a 2 year old Blue Ox.I have a procedure where I insert the pins and the small pins with the ring. Then I connect the safety cables and the electric wires. I then do a check that everything is connected properly. I even grab the tow bar and shake it. All was good and we hit the road. About 10 minutes later I glanced in my left hand mirror ( I check both mirrors every 5 minutes or so). My heart stopped as I saw my PU half way into the left lane! I applied the toad brakes slowly and took my foot out of the throttle. Not much traffic on tis road and I managed to get stopped. The front bumper of the truck had a few scrapes. The MH was fine. The left hand pin was gone. I carry spares. IN 15 minutes we were back on the road. When we returned to our home I checked the road in front of the house were I hooked up. No safety pin. At first I blamed myself but was sure that pin was secure. Did some Googling and apparently others have had this problem. My instructions for my first Blue OX stated that the pin should have the locking part on the inside. My new bar states it should be on the outside. I do know that the pin moves as often when we stop to unhook the head of the pin is tight against the brackets. I was going to use the locks shown in one of the posts but thought about a fire and just ordered new pins. I am going to change them every 3 years. I still don't know if the safety pin broke or the locking pin?

Moisheh