Work Discrimination

I am a service advisor for a dealership. A

position that is normally held by men. We

are graded by our repair average dollars. I

have been doing this job for ten months

and the last couple of months have been a

little slow and my average is a little low. I

was written up last week for this. However

one of the other guys that has been here

for sixteen years and always goes to lunch

with the boss did not get written up and his

numbers are always lower than mine and

are lower than mine now. I have all the

daily reports showing this. Would this be

considered discrimination?