that is really unfortunate. if your spouse is a Canadian citizen, then the Canadian passport showing the date of issue and all that, should have been enough. If that is the only thing highlighted, then yes, an explanation letter along with the application would be my best suggestion as well. Unless someone else has been through the same thing and suggest something better. Also, it would be best to just order the paperwork like how it lists on the document checklist so that they don't miss anything, if you did not do that already. Sorry about all this. Hope it processes quickly the second time around!!