I think your DH's hypothesis is plausible. And frankly, if the correction doesn't stick now that the case is "resolved," I'd expect that you can get the Dept of Ed on the phone; they know about you now. (We had to do this at one point, and boy did things get fixed after that.)

Right now, the least stressful option for you is probably a kind of quiet watchfulness. Give them a chance (again, I know) to do the right thing; but also continue to keep good records.

How is your DD doing now that she's getting the supports in the IEP?

DeeDee