Low Coolant lite 99 SS

Just a word of advice to those who see this warning light. I store my SS over the winter and last year, approx 5 yrs old, I got this warning light. Checked coolant and found it bright, clean, and full. Worried about this and watched temp gauge for weeks. Finally took some long cotton swabs, like the doctor uses, and reached down into the radiator to where the sensor screws in, gently brushed the sensor clean and the light went out and hasn't come back.