Inflation was a lot higher over the last decade than the "official figures", because food, fuel, and housing were removed from the index. Under the same rationale, fuel and housing price decreases shouldn't be figured into any "deflation index" - so either the books were cooked all along (which we now know to be the case), or this sectors' deflation is just an adjustment to reality.
My economics teacher in college pointed this same thing out 4 years ago. He already viewed the Federal Reserve system with a bit of disdain and was concerned that the various indexes they use to measure things were inaccurate at best.
I learned a lot in that class. The main thing I learned was to not trust any numbers without finding out exactly where they came from.