2009 GMC Acadia DTCs P0008, P0017, P0018

Those are all correlation codes, meaning they are set when the PCM doesnt think the cams and crankshaft are timed properly. Since itis so new and low mileage, I would let the dealer handle this under warranty. Without a scanner to watch what is going on, it may be the crankshaft position sensor, but there is also a Tech Service Bulletin about camshaft end play which could affect the cam position sensors reading