I brewed two gallons of a APA on 9/26 using Denny's Fav. The recipe OG is 1.054 and FG was supposed to be 1.011. I bottled today, checked the FG and it was 1.020. Post boil OG was 1.053. What would cause the FG to be that high and off? Could it be bad yeast? I ordered the yeast and it arrived swollen and out-dated (April 2015). I made a starter and pitched into two 1 gallon carboys. I only checked the FG on one carboy but now that i think about it should have checked both. I did sample the beer and it taste good. I also checked the hydrometer in plain tap water and it was 1.000. Any reasons why this would have happened?