Small update - finally saw the teacher today after school. I needed to ask her about something else and after we talked about that, I just said "I wanted to ask about that spelling test to see what was going on with that."
She basically said that test was during the week when he was acting worse than he usually does and that he had been called over 2 times to take the test and he didn't come to the group. He got his third and final chance and took the test. She said she thought about that grade. I think she was just fed up with him that day, honestly even though she knows about all his issues.
I didn't ask for the grade change and just explained as I did up above what he did so she knew. I don't know if she will change it or not. DH is still not happy because they are supposed to be testing him on spelling. I guess we will see - it doesn't really matter in the grand scheme of things I guess. If his spelling average at the end of the year is like 75% or whatever then we will know she kept the 0. If it's 99%, then we will know she changed it (since he usually get 100% or misses just one).