Mistake in Obamacare accidentally extended Medicaid to up to 3 million

Does anyone still believe the original cost estimates of Obamacare? 3 million times $10,000 is $30 billion per year, say well over $300 billion over 10 years (actually much, much more because these costs will rise over time) ($13,770 for family coverage in 2010). The Associated Press has the story here:

President Barack Obama's health care law would let several million middle-class people get nearly free insurance meant for the poor, a twist government number crunchers say they discovered only after the complex bill was signed.
The change would affect early retirees: A married couple could have an annual income of about $64,000 and still get Medicaid, said officials who make long-range cost estimates for the Health and Human Services department.
After initially downplaying any concern, the Obama administration said late Tuesday it would look for a fix.
Up to 3 million more people could qualify for Medicaid in 2014 as a result of the anomaly. That's because, in a major change from today, most of their Social Security benefits would no longer be counted as income for determining eligibility. It might be compared to allowing middle-class people to qualify for food stamps. . . . .