Answer: Yes. From IRS.gov:
The credit must be repaid if, within three years of purchase, the home ceases to be the taxpayer’s main home. For example, a taxpayer who claims the credit based on a qualifying purchase on Sept. 1, 2009, must repay the full credit if he or she sells the home or converts it to business or rental use at any time before Sept. 1, 2012.
This is but one simple, straightforward scenario. What if the buyer bought in 2008 or 2009? There are a number of "if/then" different scenarios depending on when the person bought the property and what they're trying to do with it. Thankfully, the IRS has helped answer some of these questions with a couple of handy articles found here and here.
We always recommend you seek out the advice of a tax professional with any questions specific to your situation, but hopefully this post arms you with the basic information so you know what questions to ask.