Need help: question about lien

We bought a new house on March, 2007. On March, 2008 a repair work was done under the warranty. But last year the builder was bankrupted. We just found that on Aug, 2008 a mechanic lien was filed against the builder but our home was listed as the builder's property.
Is the lien valid since as the work was done the title was transfered to us already. What should we do to clear the title?
Thank you!