I'm half joking. Not stating this as fact, just something I read. http://www.newscientistspace.com/channel/space-tech/astrobiology/dn1091
It was just one of many experiments on the Viking lander. It may or may not have discovered life, but the team of scientists on the mission decided it was just an anomoly, or wasn't important, so thats why there was no big fuss.
wouldn't the change in temperature and light during the reading trigger changes like this? could have nothing to do with life at all, just the conditions of the environment changing chemical reaction rates. just a theory
http://www.space.com/scienceastronomy/solarsystem/mars_tharsis_011009-1.html We are leaning more about Mars every day. There was the "microbes" found in martian rock which nobody has conclusively decided yet that they are actual fossilised microbes or just pretty patterns in the rock.