The Obama administration said Thursday that the Patient Protection and Affordable Care Act had 7.3 million paying enrollees as of mid-August, down from the 8 million figure they've been touting since the end of enrollment in April.

Centers for Medicare & Medicaid Services Administrator Marilyn Tavenner gave the updated figure to the House Oversight and Government Reform Committee. She didn't specify why the number had fallen, but it might be due to those who signed up for coverage but never actually paid their premiums and got kicked off their plan. Others might have since found coverage through other sources, including employers.

"Each month, this number will change slightly as consumers transition in and out of coverage as their life circumstances change- everything from getting a new job, to moving to a new state, or becoming eligible for Medicaid or Medicare," Tavenner told the committee.