attenuation of WLP810-high FG?

Made a batch of Cal Common two weeks ago. Pitched yeast starter built up twice, and fermented two weeks at 58-60 degrees. Krausen fell after only a few days and what appeared to be vigorous fermentation. When I racked into my keg yesterday, I took a reading and it was at 1.020. Does this seem like it's done? I haven't used this yeast yet so wasn't sure what to expect in the way of attenuation. 1.020 seems high to me, and the beer tastes pretty much done although "green". OG was 1.056. Thanks in advance for any input...