Most everything no matter how ridiculous will be told. Prospecitive CYA, a lesson of 9/11 for bureaucrats.
Even if true I'm not too worried. I bought lots of duct tape two years ago per Homeland Security advisory.
I think you've nailed it.
Since professional Dim victims such as Kristin Breitweiser and Monica Gabrielle (in cahoots with Chrissy Matthews and the rest of the media mob) were able to make such hay of the vague 'warning' of the August 6 pdb...you can bet the FBI has to go into CYA mode, possible public panic be damned.