I would have to argue that it is an issue, since there is active and unresolved (not to mention legal) debate over whether or not violence in the media actually causes harm to society or individuals. For example, and as a comparison, guns in criminal hands is a problem because the threat to individuals and society is direct and real, and there is little if any debate on that.
Not to say that the only criteria for something being an issue as opposed to a problem is controversy or debate. The other added element with violence in the media is that it is very difficult, if not impossible, to ever prove a direct cause and effect link, or even a periphery influential link, between violent images and violent actions undertaken by those who view them. This most likely permanently places this subject in the category of issue rather than problem.
Not to mention the fact that violent criminals we cannot ignore, should they choose to assault us. We can turn off the TV or walk out of the movie.