> Given the scope, keeping this quiet is no small task.

Rumors of widespread data collection -- even specifically by the NSA -- from many of the providers at issue have surfaced many times, what was new recently is the same (or substantially similar) bits of documentary evidence substantiating and connecting those rumors.

So, to all appearances, it may not really have been "kept quiet" up until the recent leak, it was just that the information that got out before wasn't as well-supported and therefore hard to dismiss.