I think that if she has already told you she is upset or indicated that by her behavior then you should step in. You aren't referring to a specific conflict that a child might be able to "work out" with some guidance from the parent. You seem to be identifying some pervasive issues such as being the only GT kid in the class, not being challenged and feeling as though she doesn't fit in with the other kids. Those seem to be bigger issues that a parent should address with the teachers and staff at the school.
I suggest contacting the GT coordinator and her classroom teacher. Find out what they see, if anything. Then talk with your daughter about what she likes and doesn't like at school. Look for options to help her connect with others that are like-minded. Are there options for enrichment classes at a CTD or like place? Can the teachers differentiate learning experiences more for her? I agree with the questions posed by MON - you need to explore more as to what is going on and then you'll know better how to proceed.
Keep us posted.
