Didn't Deffeyes also define the peak as an average over a 6 month period?

If he didn't he should have. What if the production data were reported weekly, or daily. Where is averging in all this, to discern the trend from the fluctuations? The trend is flat production. It'll take months or more to say otherwise. It's only years from now, averaging out the noise, that we'll put a month/year on peak. But it'll be academic.

It was either Cambell or Deffeys who said that peak should be indicated by whether producers are able to sustain production for at least 5 years.

I also think that this event develops on at least year-long scale. Month to month variations are too minute to indicate (almost) anything - pretty much like following day-to-day price variations.

I would appeal though that we should be equally fair on both sides - a dip in output in one or several months is as much a proof to the "peak-oil-now" theory, as much as a similar short-lived growth is a proof to the opposite.