I'd be just as worried about use of 'good' for a comment about LITERACY! Doesn't the teacher know any other words, or at least have access to a thesaurus?
Are dd's ideas actually 'good' (as opposed to evil) or are they 'interesting', 'exciting', 'clever', 'unusual' or 'well thought out'? Fair enough the teacher is busy but I hate seeing 'good' everywhere (except for message boards, where it's extremely easy and good to use good )