I've been noticing on some movies, it seems they weren't really paying attention to mic levels. Special effects/explosions sound awesome, but sometimes in scenes where there is yelling dialog, there will be crackling/clipping in the center channel.
I don't listen above -17 on my receiver and my center is also set at -8. It is repeatable and happens in the same spot within the movie. Apparently some people can't hear this sound, but once you do, it is awful. The RP series is ruthless with showing poor recordings, so these sounds just can't hide.