It depends on how tangental it is. If its a caller who called a caller who called a caller and is 4 layers removed from a direct connection to the terror number, then its absurd and a waste of time for them to tap that line. But if you are 1 layer removed, and after every call that our direct link caller makes to Osama, he calls you a minute later, then there is reasonable cause to be suspicious. Should we get a warrant for you so we can see where else you are calling. No.
And, just to be clear, I'm talking about the 'tangential' types we've been discussing. NOT those who called terrorists and are called by them. And NOT those who are called as a pattern right after Osama calls our suspect. Simply those who happened to get caught up in a big net.