Good Evening Professor,
I write to you as I am concerned that an error may have occured relative to my grade. The grade I have received is a B-, however, according to the rubric and returned documents the grade I have earned should be an A. I would like to discuss this in person rather than through e-mail. If possible, I would like to meet during your office hours at your earliest convenience. If an appointment cannot be made, then I will pursue this reevaluation via e-mail.