The point has been made that security is never perfect, like everything else in life.
As regards the FBI involvement (or lack of) in the Boston case, well a conspiracy theorist might see politics involved somewhere.
Anyway, the point I would make here is that if we obsess about security to our own cost, we end up doing half the terrorist's work for them.
If a couple of smack head toe rags slip through, is it really time to re-jig the world's security proceedures?
Still I bet the chance was missed to administer some suitable advice round the car park...
And I bet they don't get unlimited detention at Guantanamo Hotel.