If the audio were delayed compared to the video, it would be less noticeable. But since the sounds are actually heard in advance of the image, it stands out as unnatural. It may not slap you around the head and say "THIS AR RONGZOR!!!!!11!" but I surely can see the discrepancy, and not just with voices either. RotJ does have a bunch of bad lip synch with ADR, but this is a separate issue.
I'm definitely going to try to correct it.