Post-bin Laden Terror Scare-Real Or Imagined?

Is it because since the death of Osama bin Laden we are again paying so much attention to terrorism that we are overdoing it, or are the recent news stories indicating many new threats?

CBS news is reporting transportation systems are on even higher alert post-bin Laden because of fear of terrorist retaliation.  Of course we must be vigilant--but are we being paranoid?   A Dallas area DART or Dallas Area Rapid Transit station was evacuated and a man detained by authorities because he asked for help getting some packages aboard one of the trains.  The packages turned out to be benign, and officials said the man was simply trying to get them home.  Numerous other stories are circulating about shutdowns of transit systems, and other disruptions due to "suspicious" packages or other issues.  Some are beginning to wonder if the line between paranoia and vigilance is becoming blurred.