RE: Is this normal
Yes. Entirely normal. It means you were probably driving enthusiastically towards the end of your drive, in any case one way or t'other the battery got warm. As you charge, it only gets warmer.
So there is a Peltier cooling system to manage the battery temperature when charging, which I have noted consumes around 600W when operating, but only when charging. So if you want to be a bit more efficient, don't plug in straight away after driving but wait a while for natural cooling of the cells, then the system might not need to kick in the cooling.
I've posted at length on it before. I have established that the system draws in outside air from around the rear RHS wheel area, circulates the air through the filter (that is the 2-yr service item replacement) passes it by the Peltier heat sink, and then vents it into the cabin space. It can make for quite a warm cabin when the weather gets warmer.
I believe the gauge will hit 'zero remaining' once it is in the final 'constant voltage' phase of charging. About 45 mins before the end of charging, the drawn current (which is usually a constant 15.2A for the main 'constant current' charging phase) begins to ramp down in a series of gentle cycles until the battery is full. The cooling will continue beyond the end of the charging, but if you unplug then the cooling stops. I would not suppose the cells get that warm at the slow charge rate the Fluence works at, and suspect it is just fine to unplug once the car indicates a full charge. I'd tend to leave it an hour or so, though, to help keep the battery temp happy.