2000 Auto. Trans

I have a 2000 Ford Ranger, XLT SuperCab, 3.0Ltr, 4x2 V6...123,500k on her. I had the transmission flushed at around 50,000, and just recently about 119,000. Probably 70% of my driving is highway luckily, but I have heard some horror stories recently regarding transmissions. A friend of mine told me that he had his transmission flushed out at 50,000 and not 3 weeks after the work was performed, the transmission fell apart. He said his mechanic told him that the problem was the flush just stirs up the metal shavings collected at the bottom of the trans. case, and in turn clogs the filter up w/in 5000k...Causing the transmission to go. I did some more research and have found several more people have had the exact same problem, truck is fine until the service, then all heck breaks loose. I always have the Ford Dealer do any major service on my vehicle, such as the trans. service....Anyone have any information on the subject?....Should I be worried about my trans. going?....Anything posted is greatly appreciated.