Is a presumption rebuttable if it is never rebutted?

The Seventh Circuit today yet again affirms yet another within-guideline sentence as reasonable in US v. Hankton, No. 03-2345 (7th Cir. Sept. 7, 2006) (available here).  The opinion is intriguing mostly because of the exasperated tone it seems to take in response to a defendant's claims that his within-guideline sentence might be unreasonable.  This line in one footnote of Hankton really caught my attention:

[W]e dismiss out of hand Davis's assertion in his brief that Mykytiuk "sends the message that a sentence within the Guidelines will never be reversed...."  Our holding in Mykytiuk [which announced a presumption of reasonableness for within-guideline sentences] implies no such thing.  A "rebuttable presumption" is just that, "rebuttable."

I suppose it is accurate to say that announcing a presumption of reasonableness does not itself send the message that a sentence within the Guidelines will never be reversed.  Rather, it is the fact that, in the Seventh Circuit and in nearly every other circuit, a sentence within the Guidelines has never been reversed as unreasonably long that "sends the message that a sentence within the Guidelines will never be reversed."