Just to add something to my earlier post, I've been doing a bit of experimentation, and the results suggest that even if you haven't encountered the problem, as I hadn't, it will be worth replacing your disc regardless.
My current set-up has the Blu-ray player decoding the HD audio, then passing it to the amp via multichannel analogue outs. When watching the problem section before, when the issue first arose, I did not notice any significant problem. However, after reading some posts on another site, and wanting to double check my copy before phoning the replacement hotline, I had a fiddle with some settings.
Testing it again using multichannel out, there was again, no real problem, though there were one or two instances that didn't look quite right. However, I then switched off my amp, and turned the volume up on my TV, letting the HDMI from the player to the TV carry the audio. Re watching the same section again, the audio was suddenly out of sync by miles in some places.
What exactly the problem is I'm unsure, but it suggests some issue when the audio is output via HDMI. What it also suggests is that even if you don't have the issue now, it will be worth changing your copy, as if you change your equipment in the future, it may become apparent for this reason.