High Finishing gravity for a dry stout

I just checked the gravity of a stout that i brewed last wednesday. it came in at 16 from original at 48. This seems high given i pitched onto a full cake of yeast from a prior batch (s-04) and i mashed at 149. I fermented at 66-68 degrees in my temp controlled fridge as well. The yeast count and mash conditions point towards higher attenuation, i guess the culprit must be the grain.

My recipe is a straightfoward guiness clone:
6.25 lbs pale ale malt
2.5 lbs. flaked barley
1 lbs. roasted barley
.25 60degree crystal

I've got my eyes on the roasted and flaked barley, are these ingredients less fermentable?

To forestall some possible suggestions: my thermometer was calibrated prior to mashing, and my hydrometer samples were corrected for temperature (and really that could only swing about a point anyway).

On the brighter side, the sample tasted spot on, and it had a noticably creamy mouthfeel, i think it could go in a keg right now actually!

Looks to me that you did everything right to get a very fermentable wort. I would expect that beer to finish at 1.010 to 1.012.

Have you calibrated your thermometer? Perhaps the thermometer is off and you actually mashed higher. That would explain the high finishing gravity. I would check that first.

The good news - the beer tastes good - so, no harm, no foul.

in addition to calibrating your thermometer maybe calibrate your hydrometer as well.

I just kegged a dry irish that finished at an abysmal 1.020 down from 1.052. All my equipment is calibrated, I mashed at 153, and I pitched a half gallon starter.

Not sure what happened, but the good news: the 3 week old beer is already tasting delicious.