Reminds me of my somethin' my ex-colleague came up with in a discussion over lunch.. Trust is a complex variable. it has some real part/value that both the parties involved can be secure about, and an(two??) imaginary part where both the parties have a guess about what else they will/can trust the other about.. In this case, i think the filenames would count as imaginary part. Not to imply, it's not private, but would be surprised if it had been in the terms of service..