Difficulty has slowed in growth.
I recommend you not look at the next difficulty adjustment coming in 3 days. Or the next few coming after that now that ASICMINER is starting to flood the supply chain which will soon find its way into user's hands.
I have seen it. Difficulty growth has slowed, it is like your argument not to base "luck" on one day. Do not project the curve based on past growth nor on 4 or 5 wafer lots. I believe it will slow (especially if we can visit $400 again).
The slope of the curve is changing.