No Green Light on gear, after sitting for a week

[Skymaster337B]

Has anyone ever noticed an unsafe gear indication during the cockpit preflight? But once started and push the handle down, the green light comes on and will stay one for the rest of the time. But then after the flight, let the airplane sit until the following weekend, and the green light no longer comes on when you turn on the batttery switch. But once again, crank it up and push the gear handle down and everything appears normal.