I had a similar thing happen last night. Driving home after the car sat outside all day right about at 0F. The battery temp was just one bar (although I have seen no bars in previous winters). I had driven about 15 miles and was at about 24% leaving a stop light, not quickly or anything, I got the ding and turtle, I was about 1/2 mile from home. I slowed down to 25 (a 35 zone) and made it home and charged it. I totally didn't think to check Leaf Spy at the time, to worried about making it home, but I am guessing this is the same sort of thing, one cell lower that kicks the car in to turtle? I do charge to 100% daily, often more than once driving about 100 miles a day, with a lot of 15 mile trips. I have to think the cold must mess with the cells, some more than others? This morning I had a 12 mv spread. I will check it tonight and see if any are out of whack.
3 kw solar pv - XW6048 - eight L16's
4 ton GSHP - 1 ton ASHP
2003 VW TDI 200k miles - 52 mpg lifetime
EVSE level 2 - Clipper Creek HSC-40
2013 S model with QC package Mar of 2013
lost first bar @ 72k
@90k miles - 54.71Ahr - 83.64SOH - 78.44Hx - 237GID