Maybe those few problems were there all time and she corrected them with time. Any time you put an employee or anybody under a microscope you are going to find a flawed human being. Are you so perfect too?  Can you put others under the same scope and get a good reading? When I was involved in a traffic accident when I was 40, that also included a head injury, my friends said I was different, but for the better. My best friend said if all it would take was a hard knock to the head, she would have beaned me a long time ago. Not saying there's nothing to worry about, but this experience may have altered her emotionally, intellectually in some way, if her work is acceptable then give it time. My Employer doesn't demand my work be perfect 100% of the time, because those odds are impossible, I deal with too many variables.