I have read about this, as well as remember as a kid sitting with my grandparents at the kitchen table when I heard the news about the ALH84001 meteorite from Mars found in Antarctica. I am pretty sure that there was life on Mars at some point, however I guess we need more conclusive proof.

It's the same thing as the pre-Clovis peopling of the Americas hypothesis. Older sites have been popping up around for decades now, however the dating could always be interpreted in a way as to leave doubts. Only this year, the footprints found at White Sands gave conclusive proof that the Americas were settled thousands of years before the Clovis culture at the end of the last Ice Age. We need a similar smoking gun on Mars.