Should I have tax due on interest income in Canada which I have already reported and paid tax on in my 2017 US tax return?

Hello,

If you've already reported and paid interest income in the US, you don't have to do it CANADA. You'd have to have used proper US form in your US report. 

I also talked to someone at CRA. You don't have to file a return in Canada for income reported on an NR4.