As an act in isolation itself it's nothing. However it is the last and final, and to many apparently pointless check in a long list of intrusive measures. People are pretty hacked off by the time you smile sweetly and ask to see the same thing that was checked often less than 30 seconds ago. OK that's the procedure and I guess it has reasons that the DFT require it, but in the real world it's a pain in the arse.