Orson, you can call an IEP meeting anytime to amend the IEP. It's like the Constitution-- a living document-- and it gives you the right to ask for amendments. If you need that specificity about when the aide is there, ask for it.
If you have direct evidence that this teacher violated the IEP, and you think she's not treating your child OK now, I'd encourage you to ever so nicely take action about that. You don't have to go in with guns blazing, but you can talk to those who supervise her work-- whether that is the principal, or the supervisor of gifted services in your district, or those who enforce IEPs in your building and district-- and let them know what's going on.
We have found it useful to have a hired professional advocate work on this stuff for us-- not because we can't, but because the advocate appears to be less biased, she can get things done that we cannot.
Good luck--
DeeDee
