I'm very suprised, I believe you, but I never had such an occurance happen ever to me, and I never worried once about it. Not even my cheap free android phone NAND failed in such a way, and I was given a microSD that had write disabled but had all the data left to read off it (not my data didn't care about it), but I never had any bad experinces with flash memory in my life.

Don't forget external drives for data!