Erlotinib in Patients With Resected, Early Stage NSCLC With Confirmed Mutations in the EGFR

* Erlotinib is a pill taken daily and participants may continue to receive erlotinib for up to two years, as long as the cancer does not return and they do not experience any unacceptable side effects. * While participants are receiving erlotinib, they will be asked to return to the clinic for study visits to monitor the status of their disease and their general health. For the first 5 months of erlotinib, they will return to the clinic monthly. After that they will return to the clinic every three months.