At 12 years old now, I'm betting some of the outboard compartments are holding water, and, through the weep holes, it's eventually making its way back to the bilge. The culprit is most likely leaky bow rail fittings.
I'll probably just ignore it then. But I've always been curious...where exactly does it suck water in for the livewells and washdown?
You'll also see one of these threaded on top of that...Exercise the handle regularly, and if the boat is left unattended in the water, close the valve!