Good question. The cases I've seen are because the aircraft did a tail strike the flight before, and it damaged the trim linkages without the person knowing. So the next time they took it up, it was a catastrophic failure. I can't say I've seen everything in good working order, suddenly failing, which is why your situation appears to be a unique one, unless the trims got damaged on some kind of bad terrain tile in the scenery you were in. This has also happened before. Just make sure that when you load the first time, the aircraft doesn't "drop" onto the scenery ( a sign of bad terrain) and you don't pop any wheelies. It's definitely not a common occurrence.