My 2010 Sierra 1500 5.3L has the same tick at startup, but only occasionally and always in the cold weather months of Dec-Mar. In my case, it's a lifter and is related to the oil delivery dispersion. It started with about 20k miles on the truck and remains today at 67k. Ironically, I've run full synthetic oil through it since the 7500 mile mark, so I'm not sure if it was ever preventable. I've also noticed that it doesn't happen at my camp where I park the truck on a side hill leaning towards the driver's side, so I'm guessing a little oil is staying up top when parked this way which prevents the lifter from sticking.