There are a couple 0f issues GM is looking at for possible areas of concern with the Gen III engines.
1. Needle bearings from the rocker arms coming apart and ending up in the oil pan.
2. Oil pump pickup tube O'ring splitting aerating the oil.
3. Piston issues from excessive carbon buildup on the ring-land sides.
Most engine noises on initial startup are not " issues " with these engines but a continuing noise is a problem.