Mainly because NASA has a ton of data to analyze would be my bet. They may not have actually looked at it seriously for a good long time. Also, for proper scientific stuff, it's much better to do a little analysis, a little peer review, etc, before releasing to the media. It's kind of bad form (and bad science) to just go screaming to the media with raw data.

I am the Doctor, and THIS... is my SPOON!