Could be something in the software and logic controls that didn't like the starting sequence.
If I shut mine in AWD, and without touching the control knob restarting and shift into D it is still in AWD. Just a guess, but maybe if parked in AWD and then shifted to 2WD while still in P before shifting to D and moving the vehicle something will screw up.
The Silverado is quirky also.....if parked in AWD/4WD and the control knob is accidenrtly turned to 2WD with the engine off, it remains in AWD/4WD and won't shift to 2DW until the control knob is turned back to AWD/4WD shifted to D and then shifted to 2WD.
Current Chevys -'16 Silverado LT;'18 Malibu LT Redline;'18 Traverse Premier Redline<br /><br />Previous Chevys:16 Malibu LT2 '17 Impala;'16 MalibuLT;'15 Camaro LS;'15 Traverse; '13,'12 and '07 Avalanche LTs; '11 Tahoe LT; '13 &'11 Malibu LTs; '08 Trailblazer;'06 Colorado WT..... Chrysler era.....'80 Citation;'75 Impala;'72 Chevelle;'69 Camaro R/T;'65 Impala SS;'62 Nova