I noticed this noise when I was replacing the tensioner, pulley and belt in my 4.8is (2005).
https://streamable.com/z3iy4 the noise is when rotating it side to side quickly. It spins smoothly and I don’t feel any notching in the bearing. There is also no front to back shaft play.
Is that bad? None of the other pulleys make any noises.
The main reason why I replaced these parts it’s because the belt was squeaking. The squeak is completely gone now.