In my experience, grades in grad school were a pure formality. You were there to do research not classwork, but the college required grades and you needed a B

In my experience, grades in grad school were a pure formality. You were there to do research not classwork, but the college required grades and you needed a B average to stay enrolled, so half the class got As and half got Bs. As long as you passed your quals and kept your advisor happy with your research, no one really cared about anything else.