The tick sounds like hydraulic roller lifters that have sticking bores. It is hard to make a hydraulic roller lifter that is both light and strong enough for +6000 rpm operation like the 5.7 allows. Add to this the fact that many 5.7 Hemi's are run up to 6000 rpm during test runs when they have very few miles on the engine and you have a great potential for damage to the smoothness of the lifter internal bores.
The lifter is the most percision fit in the entire 5.7
I always 'baby' my new engines for the first 5000 miles. The old advice about 'breaking in the cam' is mostly wrong now with rollers, and the coated piston rings seat quite well without special treatment. But the internal piston inside the hydraulic lifter is still something that needs to seat well before it is stressed.
There have been many reports of 5.7 Hemi's breaking valves and springs after the engine has 10,000-50,000 miles. I suspect at the root of these failures are hydraulic lifter problems that were created in the first 500 miles.