Based on the link provided in SJackson’s post #85, I think the Mint is concerned about multiple factors that make these “appear” genuine U.S. Mint issue as opposed to privately minted (and overpriced) metals. I see it as a pattern of intentionally misleading consumers as opposed to one single technical error.
http://www.usmint.gov/consumer/index.cfm?flash=yes&action=HotItems
But, I think we can agree on “scam, scam, scam.” I’m no currency law expert, so I can’t say which violation puts them over the legal edge - I’m guessing “all of the above” is a safe answer.