It all depends on which yeast you used. That's an attenuation rate of ~64%, which is fairly low, but not unreasonable. Different yeast strains will have different attenuation rates, or amount of the fermentables (sugars) they will consume and convert to CO2 and alcohol.
When you have a question like this, it helps to post the recipe you used as well as any other information you might think is critical (i.e.time and temperature of fermentation).
BTW - welcome to the world's greatest hobby/obsession!