You may have had it 9 months, but it may have been in a warehouse for years.
I believe it is plasticiser migration. Whenever we get this issue we just throw it on the solvent. Only ever had it on old media’s that have sat about for a long time.
Coatings can degrade over time. Some media products have a date of manufacture on the box.
I would not expect an art canvas to contain plasticizers. Most digital print art canvas medias are made from cotton/ polyester blends. In this industry, plasticizers are put into PVC-based print medias to promote media flexibility - without them, PVC is fairly rigid, as is the case with PVC sheets and PVC irrigation pipes.