BTW, I just came through on the CZ about 10 days ago. I saw no sign of police in my sleeper car, but I had discussed the situation with a breakfast companion in coach, and here's what she reported to me later:
Two policemen boarded in Reno. They came through the train as it left westbound. They homed in on a young man just a couple of rows away, and asked him politely ("Now, we know you're just a fine young man, wouldn't do anything illegal, but would you mind if we just looked in that bag..."). He gave permission (she said he looked scared, and she figured she had a right to watch and was just kneeling on her seat looking back two rows at them), and they searched the bag. Then they went into the vestibule of the next car up, and had a discussion between themselves. They returned two more times, each time asking to see more, till they had gone through everything he had. Then they asked him how much money he had with him ("not over $1,000?"). Then they left him alone, and got off at Truckee.