oh Becky - your email brought back what my son went through in his Montessori preschool not long ago....my son SO wanted to do the "advanced Montessori work" that his teacher refused to teach him (even though she said she was very aware he could do it, she was just afraid because he was already so advanced that if she taught him everything he wanted to do at that time, she would have nothing to work with him on if he stayed for kindergarten - absolutely ridiculous and she should have been fired)...so she gave the excuse to my son that he needed to be 5 years old in order to do those activities. For over 6 months he went around saying he couldn't wait to be "5 year old smart" so that he could finally do some "fun" work. This then turned into where he was worried about pulling out his favorite games at home that were marked ages much higher than 4 years old on the boxes - he was afraid he would get in trouble for playing them since he wasn't the "right age". His teacher would also get upset at me in front of him and state that I shouldn't be allowing him to read such advanced books because he is already too far ahead of the other children...I didn't think he had heard her but it turned into an issue because later that week (and for several more weeks) when we went to the bookstore, he very much wanted to get a book he found but he was worried that his teacher would get mad at him for reading it.
needless to say we are no longer at that school and it has taken about 4-5 months to undo the damage that one teacher did...he now no longer worries about whether or not he is allowed to or old enough to read a certain level or do certain activities...we just talked constantly to him about how different people are able to learn at different levels. I just know exactlty what you are going through!