Practical Travel Safety Issues - OK to use "stale" BP for standby?

Southwest has a policy to let you standby for no additional charge if you miss your reserved flight by less than 2 hours. Previously I had no problem passing security with a boarding pass for a flight that had just departed. Last time the TSA people told me I had to go back to the ticket counter and get a gate pass.

This sounds incorrect to me. Does anyone know the official policy for slightly stale boarding passes?

Wirelessly posted (iPhone: Mozilla/5.0 (iPad; CPU OS 5_1_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9B206 Safari/7534.48.3)

Just tell them the flight is late.

Not sure I would lie to them.... probably not good if you get caught.

Wirelessly posted (iPhone: Mozilla/5.0 (iPad; CPU OS 5_1_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9B206 Safari/7534.48.3)

Just tell them the flight is late.

Just tell them the flight is late.

There is another post somewhere here that describes how TSA refused to allow someone to clear security for a flight that actually was delayed, because it was after (or too close too) the time printed on the boarding pass.