Never did this in P/C
Had door come open on '53, tho.
Picked up on relay from CACH. Did proper pre-trip (yes, even on relay set. Never did trust meet drivers. Found flat tires, missing, not just out, lights, numberous other problems). ALWAYS checked latches and handles. Found some doors that weren't closed properly but sealed, sealed but wrong numbers,etc.
Almost home, guys in a car passed, waving something. Close behind, truck passed. Saw he was on CB so I turned to 19 to ask if he was talking to me. Said one door was open. I asked if anything fell out. He said he didn't see anything. Pulled off and found right door (first one to open on rail box) open. Actual latch bolt (only one latch, compared to some that have two) had broke, handle bounced up, causing door to open. Never did swing out so I could see in right mirror (because you know I always check mirrors every 5-8 seconds).
Luckily, 100% load was tightly load-retained (which shocked the hell outta me, being a CACH load. They NEVER strapped loads down. You listenin, cachsux?). Bungeed door shut as best I could and made it in.
As a funny. LP swarmed that trailer like flies on smile* when I got in. Made more money on the interogation process. Thank you.