I'm thinking that no matter what you do, you need to document this for the future in case you run into other violations that you ultimately do want to fight.
polarbear
I totally agree with this.
And personally, I would definitely follow up on it. (Not necessarily with guns blazing, but assertively state what's going on and ask for the principal's attention in resolving the issue.)
If your DS will be at the same school next year, the principal needs to be on alert to place your DS with teachers who will follow the IEP and support him. That's the big reason to deal with it now, IMO.
DeeDee