What happened is that the grease god cold enough to keep the spring from actuating the pawls. I had this happen a couple of times a couple of years ago with a cheap freewheel on my winter bike. I ended up taking it apart, cleaning out the grease, and replacing it with a lighter lubricant. The problem with this is that it'll wash out easier, leading to increased maintenance intervals.

I'd rather have a freewheel that works all of the time, personally.