There's a difference between knowing about the rumors and having something to back them up with. I, for one, would hope that no one publishes stuff like this without a reliable source. In the case, perhaps it is only the LA Times who found a source and the delay is because they are unsure if the source is credible enough to "go" with.
D.C. leaks like a sieve. If there is anything like this happening on the campaign trail, then a lot more than one person knows about it.