No one wants to find a dreaded “SSSSSS” on their boarding pass, because it means they’ll be subjected to a once-over by TSA agents. The “selectee” designation is usually randomly generated by the airline, but a ticket agent can also add it manually. And they often do — especially if they don’t like you.

At least that’s the contention of Barbara Arbani, a frequent flier and self-described “innocuous-looking grandmother” who recently had a run-in with a rude US Airways ticket agent while traveling with her daughter.

“When we checked in at the counter we asked the agent if there were any seats closer to the front of the aircraft,” she remembers. “The agent had been speaking with a co-worker. It was just a social conversation, not work-related, and she felt we had interrupted her.”

The irritated ticket agent arbitrarily picked two seats closer to the front of the aircraft. They were worse than Arbani’s original seats.

“My daughter and I said we preferred the seats further back,” she said.

The agent then harumphed, rolled her eyes at her co-worker, and reprinted the original seat. But these boarding passes were different. These had a line of red Ss stamped across the top.

“At security, we were quite surprised when we were both taken to a special line and our bags were individually opened and searched, as we were. An agent explained to us that a red ‘S’ had been stamped on our boarding passes by the previous perturbed agent. He asked us if we knew why. We said only that we had taken too much of her time, and the TSA agent smiled and said, ‘This sometimes happens.’”

I’ve written about who can and can’t add you as a selectee in the past (full disclosure: I’ve been subjected to additional screening as punishment for my behavior, too, and I didn’t like it).

As I review the available information about how you become a selectee, I’m impressed by how many people seem to have the authority to subject you to additional screening. It’s conceivable that you could be sent to the special line for not tipping the skycap adequately.