I thought about that too, when I noticed this behavior (which is common for me, except I don't ever recall the rough shutdown). But I do not see the batteries indicating charging in either the MFD or the nav energy screen. I suppose it is still possible that charging is going on, but just not indicated in these screens.

The other two things I thought of were
1) bringing the MG coolant temperature up to normal which we don't get visibility to
and
2) bringing the catalytic converter temperature up to normal, which we also don't get visibility to.