Thanks, everyone, for your insights.
I think it all boils down to the fact that now -- in hindsight -- I realize 3.5 was really awfully young to test. So while I am not unhappy with the scores she received, my mom gut is telling me they may not 100% accurately reflect dd4. Or, I could be wrong

.
But since we're in a good spot right now, I think we should have no problem waiting until the age 6-8 range to retest.
Perhaps a few of my questions will be answered this summer when the school screens the kids for kindergarten reading/math groups. I am interested to find out at what grade level the school thinks dd4 should be learning. I am just hoping that there will be others in her class who are working at her level or (even better) beyond.