<p>You need to read your offer, which shall be in writing, carefully. If it did not put a minimum 3.0 GPA as a contingency for employment, then you need not worry about that. Anything verbal is not official. In fact, the HR person that you are in contact with now might be gone by the time you start working there. The only thing that I can think of here is that they actually have a 3.0 GPA requirement in order to grant you an interview. You somehow got in and thus this new requirement. But if it is not in writing, then it is not official.</p>