GaryW, welcome to the forum. What an experience for you in this weather as a new owner! I wouldn't read too much into this because of such an extreme temperature, and it does sound as though your i-MiEV was protectiing itself.
I've had my Mitsu Panasonic brick EVSEUpgraded
and concur with Don's suggestion for slowing down the overnight charqing, although when you turn on the Remote to preheat in the morning it means that more of the energy will be taken out of the battery to preheat the car than if you have the EVSE set at 12A.
On some of the EV forums there has (appropriately) been some discussion about charging at low temperatures. If I recall, a very low charging current at the temperature extremes was suggested, but it was unclear if this applied to all lithium battery chemistries.
As far as using the car, if you're like most of us you will soon find the iMiEV becoming your PRIMARY car, with the ICE vehicle reserved for long trips. Last Sunday for the first time in a long while I took my ICE car for a 50-mile (one way) trip to an evening party instead of the iMiEV simply because I needed to start using it's old gasoline, although I'll admit that uncertainty as to the availability of a public charging station played a factor in this decision.