The problem arises when you get the coins appraised (unless you happen to be an expert and then can value them yourself). Once a dealer knows the value of your coins, it doesn't matter if you tell anyone or not - the cat is out of the bag.
The government got those coins and I guess they will get these also.
The Philadelphia case was a little different. Those coins had never officially been circulated, so the only way anyone could have one would be if it had been stolen from the mint. The case was decided by a jury trial, and the government won.