I have just bought a used Quantum Calcu Light XP exposure meter. It's in great condition and seem really nicely designed. However, when I press the "Measure" button, the digits in the display window blink, they are never continuous, they keep blinking as long as keep the button pressed. The readings are accurate, but I am not sure if the blinking is normal. There's no mention of it in the documentation. Does anyone have this meter and can answer my question? Thanks very much!