Shifter lights not always working

[dwd1985]

Sometimes when I turn on my lights at night, the shifter lights that indicate PRND321 dont light up. Generally, if I turn my car lights on and off once or twice, or push the shifter forward to park firmly, they will come back on. But in the mean time, its kind of annoying. Its not a big deal, but what could it be? Probably just bad wiring, but I want to see what everyone else thinks.