The reason you see the dim flash is that there are many LEDs  inside the basestation, on the Printed Circuit Board that flash in a series of pretty patterns, but the plastic light-pipes that bring the LED light to the face of the front panel, pick up these flashes of light and pass them along to the front panel. You could, if it is too disturbing, open the top, and put some black cloth around these light pipes to keep them from “seeing” the flashes taking place inside the box and passing them along. Just take care not to leave it in any precarious places on the PCB.