Of course this is being done. It would be well nigh impossible for it not to be happening.
Of course they aren't interested in your Aunt Sue's recipes. But if Aunt Sue posed a threat to NSA, such as being on an oversight committee or just about any other position of power, you can be damn sure they would be very interested in everything she does.
And if Aunt Sue opposed NSA's hegemony, they could find a way for Aunt Sue's predilections to become known, without in any way having it look like they made that happen.
Google and Yahoo may have some culpability. Rather than throw open the front door, I can see where they might have said through back channels, "We can't be seen as openly cooperating, but here's a back door you might find unlocked." That's the way the cool kids do it.