Randall,
I figured that after the one complete fluid change that I did back in 1988, the fluid and original brake system owed me nothing.
And years ago, I did see worse. For some reason, the Ford Fairlane GT's with the 390 option in 1966 had the first go at four piston calipers, that lasted about 3,000 miles before seizing up. They tried all sorts of piston alloy combinations, but it was probably the fluid and the heat that they generated. That stuff came out like rusty antifreeze.