DX3600 - Blinking yellow light

My DX3600 will give a blinking yellow light instead of a green light when I attempt a picture in low light or have a low amount of detail in the center of the picture. Is this normal? From the manual it only says "Auto Exposure is not locked - recompose the picture." Not much help or explanation. Anyone have an explanation? It will take the picture despite the blinking light and it will usually come out fine. More aggravation.

CharlieP