A month ago, as I was retrieving my checked-in bag at Heathrow (I've stopped over in London from New York, en route to Bangkok then on to Paro, Bhutan), I thought something wasn't quite right but in a hurry to get a cab, it's only later that I saw that my TSA-approved lock was missing.
I unzipped my bag and saw that someone had opened all my zipped-up pouches holding chargers, batteries, cables, a sound recorder and a couple of hard drives. Nothing was missing so it wasn't a thief...but it was someone who checked every electronic item in the pouches, to the extent that the tiny SONY microphone I use with the audio recorder was removed from its little bag, and was found on top of my socks...just like that. There was no note from the TSA...nothing to indicate that it was the TSA which had done that. Since nothing was taken, I assume it was their staff that opened the lock, failed to return it, and thoroughly rifled through my electronic stuff.
Ralph Childs, a participant in my Bhutan photo expedition, had the same experience on his flight from Chicago. The TSA-approved lock was also missing, with no note from the TSA. In his case nothing was taken and his belongings weren't rifled through.
While it gives me comfort that the TSA seems to be really screening bags, and appreciating that its staff is under-trained and overworked, I am still taken aback that Ralph and I (flying from different US airports) lost our combination locks, and there was no note indicating that the TSA had been through our bags. In my case, I'm just annoyed that electronic items were strewn around in the bag...losing an item would've been a nuisance, although I could've replaced it in London or Bangkok.
Moral of the story: Keep every item you depend on for your work in your carry-on luggage...and remember that TSA locks are great if and when the TSA staff have the ways to open them (or take the trouble to)...if not, you can kiss them goodbye.