Hmmm... inneresting.
Note, however, that there appears to be no heightened water sign at the Tharsis volcanoes, and none around Solis Lacus.
It's also interesting that there is so much water sign near the north pole in the dead of winter when the CO2 cap is so extensive.
Arabia appears quite damp throughout the year, eh?
Surprising that Acidalia doesn't show much water sign to speak of.
Very interesting.
Here's another image: 
http://www.gsfc.nasa.gov/topstory/2003/0626marswater.html#
Hmmm.
What do you think is going on Bob?