I've not seen a plug in my 2008. Just a narrow PVC tube connecting the forward bilge to the fuel tank compartment.
The forward bilge is the lowest point in the boat. Water can flow forward from the aft bilge when the boat is at rest. But only if the aft bilge has a lot of water. Running on plane generally keeps the water level in the aft bilge below the connecting drain tube.
Water can get into the forward bilge several different ways. The anchor locker is the most common source. A surprising amount of rainwater can get in there that way. When I flush out my tank compartment with fresh water as recommended by Grady, a lot of water drains forward. Usually enough to activate the forward bilge pump switch. When I rinse the deck, some water always gets into the cabin under the door and drains into the bilge.
The only thing you need to worry about is a leaky rub rail. The Grady hull design pushes a lot of spray below the rub rail in rough sea conditions. I've had to re-seal the rub rail on my two previous Gradys after hard dock bumps. You can check for leaks by spraying a hose along the bottom of the rub rail after first drying out your bilge.
Since the bilge pump and switch are mounted on a high point in the forward bilge, a lot of water can collect in there without activating the switch. The forward bilge holds almost 5 gallons of water before the pump turns on. Binging the boat off plane can move the water around enough to float the switch. I pump the forward bilge out using a battery operated fuel transfer pump on a regular basis in order to keep mold under control in the cabin.
Transfer Pump