I just purchased a weather station bundle that included a lightning detector. Last night I had the first thunderstorm since I installed the unit. I noticed that when I would see a flash of lighting sometimes the interference light would come on and the display unit would flash unable to detect. Prior to this storm the interference light never came on. I have the lightning detector hanging out in the open far away from any sources of interference. The display indicates that 547 strikes occurred. The interference light continued for the length of the storm. Is this normal operation?