I've noticed Koorz re-adjusting SoC once or twice when driving a short distance (about 5 miles), parking, then going again. Maybe it's a sign of internal resistance throwing off the voltage reference of the charge level? Or just that the car needs a few calibration charges to line up the charge profile?
Bear has a newer pack with the improved cells, and I've yet to notice SoC changing while parked (outside of a .5-1% change overnight after fully charging).
"Bear" - 2012 Diamond White Pearl ES with QC - 2/21/2013
"Koorz" - 2012 Cool Silver Metallic ES with QC - 1/5/2015
"Photon" - 2017 Bolt EV LT in Orange with QC - 7/31/2017
Solar-powered since 10/10/2013