There seems to be nothing in that newspaper article that could verify the date. It could have been printed way ahead of time just in the normal course of printng schedules.
I think that the article was written in advance, maybe years before, and they took a picture of Fidel holding a proof copy so that when he died they could release the picture, while having the article printed in Granma the same day as "proof" that Fidel was alive. Someone in the process forgot to make sure that the headline color in the proof and in Granma matched, and hopefully the consequences will be far reaching because of this little blunder.