Well guys seeing my 08 is a 1lt I may just be inclined to have experienced what Vince is saying. Anyway it seems to be normal again.

 

If you don't have Traction Control on your car, you probably have ETS.

Enhanced Traction System (ETS)
Your vehicle may have an Enhanced Traction
System (ETS) that limits wheel spin. This is especially
useful in slippery road conditions. The system operates
only if it senses that one or both of the front wheels are
spinning or beginning to lose traction. When this
happens, the system reduces engine power and may also
upshift the transmission to limit wheel spin. You may feel
or hear the system working, but this is normal.
If your vehicle has ETS, there is not an ESC/TCS
button on the instrument panel. To turn the system
off, shift to LOW (L) or REVERSE (R). There is more
information about how to turn the system off later in
this section.
A LOW TRACTION message will appear on the Driver
Information Center (DIC) when the traction control
system is actively limiting wheel spin. Slippery road
conditions may exist if this message is displayed,
so adjust your driving accordingly.
If your vehicle is in cruise control when the ETS begins
to limit wheel spin, the cruise control will automatically
disengage. When road conditions allow you to safely
use it again, you may re-engage the cruise control.

 

If it is in fact a ETS system then GM saved a few hundred by not giving it a display and it still works in Reverse.
Think more likely our little trucklets have things in them that are not even supposed to be there. Don't recall if mine was a Monday,Friday build. LOL