Rerunning that test popped it to 30. It was reported as passing on my side (or else how could I have advanced beyond the sequences?) so this is a nice surprise.
Nice! Enjoy bragging about being the first person to ever beat SIC-1.
Guess I'd better get started on the sequel ;)
For the record: I'm not sure what went wrong originally (best guess is a network error, although the free service I use on the back end doesn't have logs far enough back for me to say for sure).