2007 temporary Coolant Error

[lurky]

Hi,
I have 2007 and I live in the North East. Its been getting colder but its still in the 40s-50s mostly.
For the last several days I've been getting a red blinking light on the coolant meter, and then a coolant error. this happens immediately when I leave my driveway, but the error/red light goes away by the time I drive a few blocks, and then the needle starts moving up to almost halfway.
So I topped it off with some distilled water and today I didnt get the error.

But does the fact that the coolant needle initially does not move, then after the car warms up, moves to halfway indicate anything in particular? Perhaps the anti-freeze has lost its potency? i'm about to garage it for the winter, but Im thinking about draining/replacing the coolant in the spring.
Thanks