I doubt that you have a virus. If the yellowing leaf is old, it is probably due to normal senescence.

Your canna seems to have black aphids. Aren't they moving? It is good practice to thoroughly spray outdoor potted plants with insecticide and miticide before bringing them indoors. If you have other indoor plants, they may become infested. Luckily, aphids don't do much damage compared to mites.

I really hope you're right! Thank you. I'm going to thoroughly clean it up and hope that they go away. And honestly, I couldn't tell if they were moving... yuck!

They can be really difficult growing indoors over the winter, I have tried many times and failed to keep them past November. What I do now is let our first frost get them and then I cut them down, remove the bulbs and clean them up real good and put them in brown paper bags and store them in the bottom drawer of my refrigerator, since I dont have a cool basement to store them in, that works best for me. Good luck with whatever method you choose.