I passionately disagree. The teacher's note is a direct reflection of her skills as a TEACHER. Sorry, I disagree 100%.
It's evidence of her skills (or lack thereof). But I wouldn't judge her to be incompetent on the basis of this one note. I have a graduate degree and my own posts at FR probably have an average of at least two errors per post. When I make mistakes it is usually because I have typed the post very fast and failed to review what I have written. But I am fully capable of composing complex and grammatically correct notes, essays, and posts without errors.
I am not quick to judge her note, because in haste I have written things just as bad.