I didn't realize anything was missing until after I'd landed at LAX, and was walking through the terminal. I spoke with one of the TSA supervisors, and told her my story. First, she said that someone obviously had not followed "proper procedure," as passengers are never supposed to be taken out of view of their property. "You came in on United, right?" "Uh-huh." "In that case, you'll need to contact them."
The customer service desk in Terminal 7 had a huge line, so I walked over to Terminal 8. There were three people behind the desk. "We're closed!" "I just have a quick question..." and told them my story. "You need to talk to TSA." "But, I just spoke with TSA, and they said I had to talk to you." "Well, we don't have the Lost and Found number for San Francisco, but I can give you the number for Lost and Found at LAX, and they can give you the number for San Francisco."
So, I called the LAX number, and got a recording... "our hours are 6 a.m. to 2 p.m." (at this point, it was already 1:52 p.m.) "if you're hearing this recording, we're busy assisting other passengers ... stay on the line, leave a message with your telephone number after the tone and we'll get back to you ... (beep) Mailbox Full. (click)"
I tried two more times, with the same results. After 2 o'clock, there was no answer ... the number just rang and rang.
So I walked over to one of the gates, and told the story to an agent who wasn't busy. An off-duty employee who was standing next to her said, "oh--I know what to do," stood in front one of their magical computer terminals, tapped a few keys, and gave me the number for SFO Lost and Found.
"You've reached the SFO Police Department Lost and Found. Our hours are 8 a.m. to 8 p.m." (already a huge improvement over LAX) "If you lost an item at a security checkpoint, you're in the right place unless you flew either American or United, in which case you need to contact your carrier directly." (So the first TSA person I spoke with had it right all along!) The message gave both numbers rapidly, without repeating them. I had to call back and listen to the message again.
For what it's worth, United's "secret" (from them!) phone number for SFO Domestic is +1 (650) 634-1525. You leave a message with your name, telephone number, description of the lost item, the date and time you lost the item, where you lost it (if onboard, they want the flight number, your seat assignment, and the gate where the plane landed). Then, if they find the item within 10 days, they're supposed to call you back. You're only supposed to call once, and you'll only hear back from them if they have good news.
I called my mother and told her the story (the sweater had been a gift from her). She was entirely unsympathetic. "It was an old sweater, it had already been repaired once, and needed replacing anyway." Gee, thanks.
Update: No one called me back.