Got the same email.. and since after getting the new sensors installed for Extract the truck hasnt actually functioned at all with the ride height adjustments I'm not sure exactly what else they would have changed for that capability either (and no I havent taken it back to the dealer.. was getting tired of taking it over to them since its had 4 trips in the last month and the truck is currently 'stuck' at the normal ride height).
My truck is also stuck at the "Normal" height with a "service Leveling system" indicator. It's no big deal for me right now, I figured I would wait and see if anything else pops up before taking it in for service.
The Joys of a first model year vehicle with so many new systems? It's great, but I cannot think of any other GM vehicle launched with so much new invention on a single vehicle. New Chassis, New Suspension, New Battery tech, New drive units, New control systems, I mean this is really off the beaten path for GM, and GM usually does not do this type of launch where everything is new. When they launch new truck models trucks of SUV's they usually carryover the powertrains until the next refresh, so they don't have so many unknowns at the same time.