Not really. Mostly things I have read. The $300/$600 limit to premium credit is probably not what you are referring to, but can be found here http://www.cms.gov/CCIIO/Resources/Fact-Sheets-and-FAQs/Downloads/income-verification-8-5-2013.pdf
The key to the issue of someone living in a state that has not expanded medicaid overstating their income (@<100% FPL) to gain subsidized access to the exchange policies is more bark than bite. This is the most recent (at least that I have seen) paper on income verification http://www.cms.gov/CCIIO/Resources/Fact-Sheets-and-FAQs/Downloads/income-verification-8-5-2013.pdf
Income must be documented and verified before subsidies are extended. This is done with prior year tax returns and employer pay records. If verification does not take place the policy and credits are only extended for 90 days and must be revisited. So, if there is verification and approval upfront and income changes during the year, it will be detected by voluntary self-reporting or subsequent income tax filing, but no other process is in place, and no penalty for not reporting the change.
Thanks for the information. Your first link though is the same as the second and I think you meant to link to a different page.