This is an example of a "high wet" reading on a Tartan 37. This port light has likely been leaking into the decks core. While this is not in a totally critical location the genny track is only a few inches away and was reading in the high moist range.
A high reading bellow the port light and a moist reading near the genny track leads one to believe the port light is the likely culprit as the moisture diminished the further away you got from the port light. The moisture had traveled a good 7-8" towards the genny track through capillary action though and about 12" side to side.