Does Stanford look at credit by exam grades?

Hi. I took a credit by exam for algebra 2 in high school. I am a freshman. I passed and I got the credit and the school let me skip to pre- cal. However I got an 80 on the exam and it went on my transcript. I have all A+. Does Stanford look at these credit by exam grades and will it affect my chances of getting in to Stanford? This has been bugging me for a while. Is there any way I can erase the grade from my transcript by retaking the class or something? Thanks in advance!