I just flew back from the USA, and found a TSA notice in my suitcase that it had been inspected. I could tell that they checked a couple of items, but thankfully nothing was removed or damaged.
Now the interesting thing is, as far as I can recall, I locked my suitcase using the combination lock, and didn't use the key. When I opened the suitcase, the combination lock was unlocked, but the key locks were locked.
The suitcase is a common "Polo Club" type with a key-operated lock on each latch and a 3-digit combination lock in the middle. I already know the same key works with most of those suitcases, but I wonder how they opened the combination lock.
Edit: Here's a picture of the lock. It's not broken.