It could also be that the last test they planned to execute resulted in the 'anomaly'.. Not every public communication is subterfuge even though the armchair detectives in the HN comment section always seems to think it is.
But it also sounds like kind of a bad thing that it's the last test: 'holy cow - that was close - thank god we had the last test in there.'
Without knowing the specifics of what they were testing every time that might be irrelevant, but if it was multiple test fires of the same engine and only the last one caught the problem, that's scary.