Well based on my experience of reporting to a boss > 15 years and being a supervisor myself > 7 years,it sounds like she couldn't find out things more serious than a grammar error.
Is it a good thing? Well, depends. It means one of the following things:
1. She has not paid too much attention to what you are doing
2. You have not had important work / projects that attract her attention
3. You did an impeccable job that she has nothing to pick on
1 is neutual / negative; 2 is negative; 3 is definitely positive.
