TSA Violates Constitution While Detaining Senator Rand Paul?

According to press reports, such as this one on Officialwire.com, Senator Rand Paul was detained by the TSA.

U.S. Sen. Rand Paul says he was stopped briefly by security at the Nashville airport when a scanner found an “anomaly” on his knee.

The Republican who frequently uses the airport about an hour from his Bowling Green, Ky., home told The Associated Press in a telephone interview that he asked for another scan but refused a pat down by airport security. He said he was “detained” at a small cubicle and couldn’t make his flight to Washington for a Senate session.

Paul, the son of Republican presidential candidate Ron Paul, said the situation reflects his long-standing concern that the TSA shouldn’t be “spending so much time with people who wouldn’t attack us.”

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Rand Paul’s detention provokes an important constitutional question because the US Constitution says in Article One Section Six (speaking of federal elected officials):

They shall in all Cases, except Treason, Felony and Breach of the Peace, be privileged from Arrest during their Attendance at the Session of their respective Houses, and in going to and returning from the same; and for any Speech or Debate in either House, they shall not be questioned in any other Place.