I am Danish. I moved back to Denmark September 2015. I did already file 2015 Taxes. Now Turbotax ask me to file taxes for 2016. Why? Did an error occur?

I am Danish citizen. I finished my internship in the US in August 2015. I moved back to Denmark in September 2015. I already filed 2015 taxes last year. 

Now I get a notification that I have to file taxes for this year again. Why does this happen? Can I just ignore this, or what action should I take to correct possible errors that have led to this mistake?

Thanks in advance for your advise.