Not sure of your grain bill but if it was mostly pale malt I can see it easilt attenuating that far down with a mash of 148 degrees.
Brewing since 1989 - BJCP National Rank
Fermenting: McChouffe clone, Samiclaus clone
Conditioning: Belgian Tripel, Barrel Aged Baltic Porter - in sherry barrel, Belgain Easter Ale
On tap: CAP, Dortmunder Export, IIPA, Dubbel Chocolate Stout, Wee Heavy, Whiskey barrel aged Wee Heavy, Baltic Porter