nothing to be worried about. power button light is controlled by bios. many variables contribute to voltage sent to that light.  As long as your pc is fully functional, just ignore the light.
Recently, the white power button light on my XPS 8930 has become unstable, where when I turn the pc on, the light will go out and sometimes come back on, and after a period of time, will stabilize and remain lit. Nothing else is wrong with the pc and I haven't messed with the internals in the last 2 years. Should I be worried that there's something wrong with my pc? Or is it just a case of the wiring going faulty?
XPS 8930, unstable button light