Listening for what is NOT said is just as important as listening to the actual words that are spoken. Look for it. The argument may not be about your child at all. Beware of situations where one or more of the teachers feel that their professional stature or competency is under attack. Also, be aware that there may be friction between staff members in the school that will affect decisions made concerning your child.
Teachers are very sensitive to comments from other teachers.
Teachers want and need the respect and cooperation of their peers. The teacher may be justifiably concerned that the child's cognitive development does not match the level required for the new grade. Classroom activities and assignments are structured differently for children who are concrete thinkers than for those who are abstract thinkers. Gifted children are often capable of complex concrete reasoning. But, developmentally they may not be able to make the jump to abstract reasoning.