What did you mash at? If you mashed at a really high temperature you might not have created a very fermentable wort, but it should still drop more than what it has.
You are only at 63% attenuation and wyeasts webpage says that yeast will attenuate to 71-75%
Give it some more time, it will drop a couple of points, but really its only been in there for a week. Hold your horses and let it do its thing, the yeast know what they are doing