Below is the reponse I got for Southwest on my recent inquiry/comment regarding the TSA Gate Searches:
We're sorry for the delay that you experienced in the gate area because of the additional time it took for the Transportation Security Administration (TSA) to perform a secondary gate screening. If this situation occurs and it is time for you to board, our Employees will (if possible) momentarily delay boarding as long as the flight will not be delayed. If the possibility exists that the flight could be delayed by holding up the boarding process, our Employees may ask you about your seat preference and ask the Flight Attendants to try and save your preferred seat (if available). Please know that the TSA is aware of our boarding process and our Business Select product (since these Customers receive priority boarding), and they will make every effort to perform any random screenings before the boarding process begins. Nevertheless, we apologize for any inconvenience.
Unfortunately, it does not appear that TSA is truly making every effort to perform random screening and searches before the boarding process.
In fact, recently at IAD the TSA Agents set up their table behind the Gate Agent and waited for boarding to start before they started any searches.
And, I've yet to see a SWA Employee hold up the boarding process to wait for a "random" search to be completed.