That's likely your issue. I wouldn't expect it to come down any more if you mashed that high. But that's not the worst thing in the world. Assuming it tastes OK, as Dan queried, you'll just have a high-bodied, low-ABV amber. If it tastes bad, you can try an enzyme to help break the complex sugars into simpler sugars. Bean-o is such a choice, and there are brewing-specific versiond of the same enzyme.