Dreaming of academic grades means

you are anxious about being judged and accepted for a type of measure like past school performance. You may have left school ages ago, and yet you dreamed about your old academic grades. You have hangovers from your past. You need to move on. You have to let go of the past. Your present and future depends on your on-going efforts. You might have thought you were at fault for not achieving better academic grades. This dream might be a reminder of your past