To the best of my knowledge satellite only corrects for the standard deviation from GMT. It does not correct for daylight savings time (DST). Hence the reason the setting on the head unit for turning DST on and off. A software upgrade to the head unit would probably resolve this. If I remember correctly, my Garmin self corrects.
The reason your cellphone gets corrected is that your service provider is on the same time as you are and the time data is sent by them via a cell tower.
2011 Optima Hybrid