seems your child had a formal eval from which a GAI score was posted earlier... often a GAI is indicative of slower processing speed and/or lower working memory, which could possibly be impacting your child. Have you checked with the person who evaluated your child to inquire whether his/her interpretation of the assessment results might reveal anything which the teacher could be painting with a broad brush as "immaturity"?
Also, have you asked your child for input as to how he sees the reading time? For example, if he is pulled out alone, does he feel uncomfortable in being isolated? Are there specific things which he can articulate which are "triggers" for the described behavior?
We (DH and I) had been vascillating on whether to contact the psychologist regarding this issue. He did say that the difference between Working Memory/Processing Speed and the other scores was great enough that it would technically be considered an LD, but that we would be very unlikely to receive accomodation because of it. He suggested we work on things that don't come easily to DS like soccer or baseball to help develop that part of the brain. He said sometimes he will see improvement in that score when the brain is challenged. I reveiwed the psych report and there was no mention of maturity issues.
According to DS, the reading time is one of the bright spots of his day. He works with the highest level reading group in the class he goes to. He has NEVER had a reading group to work with, he has always been the only child in his reading level. He loves the third grade class because he reads at his level with other kids.
