Some folks might say that these 2 OVA episodes are more for the people who have read the manga, and that if you've only seen the anime (season 1) it isn't worth it to watch these.
Those folks are WRONG.
WATCH these 2 OVA episodes no matter if you have or haven't read the manga. I have not read the manga; I only watched the anime. And I loved these side stories! They did a great job filling in any questions you may have had after just watching season 1.
Man, I really hope that the announced new release for next year is a season 2, and not a remake.