Yes, they replaced the lifters, gaskets, a few other things. Dealer stated that there is a TSB on it (TSB#PIP5606B) maybe? When I picked it up after the repair, it was much quieter. I have 2200 miles on it now and the tick is coming back and it sounds like I have an exhaust leak at the exhaust manifold and exhaust connection. It's going back in to the dealer Tuesday as I now have a check engine light on. I called GM Customer Service on the issues and that has been a joke..I must say, disappointed in this unit. Trying to get a couple new 6.2's to compare mine..
As far as when the noise was present, mornings and after it warmed up. A little piston slap is common on cold starts and should go away less than a minute or so. Now my tick began as a piston slap in mornings, then just got worse as I drove it more. Then it was constant, never went away. I complained about the tick at 818 miles and took it in to the dealer..they wanted a video, got it, helped then diagnose it. I will say that the performance of the 6.2 is awesome!!
I had a 16 5.3 that had a slight dry start slap, had 50k miles on it, ran like a beast.