Whoah there.... "It is implied by the fact they were carried out that they were."???? There are plenty of examples throughout history where governments have used searches (like surveillance) to oppress those who disagree. That is exactly why the 4th amendment protects against unreasonable searches and seizures without warrants supported by oath and probable cause. Leeway has been provided where the delay for a warrant (which is a generally speedy process) could be an issue. That's what would be necessary for this alleged surveillance without warrants. If thats the case, it is entirely justifiable. Not getting a warrant, though, would be a total violation of 4th amendment rights.
Justifying it by saying that the fact that the surveillance was carried out implied that it was necessary is dangerous. That allows for justification of actions such as those the KGB routinely used in the USSR and which routinely occurs in many countries today (China, North Korea, etc)...