Pops on a LD Digital Audio track

Just wondered what would cause things like this. I don't think it was the film source on the two titles that I noticed the noises. (North by Northwest Criterion CLV edition, On Her Majesty's Secret Service) The noise in N by NW is just after the credits and sounds more like an error in the video transfer. The whole audio track has what sounds like a quick skip. On OHMSS, about 3 to 4 times in Side 3 there were pops on the digital track.

Over on lddb this is listed under severe cases of rot. But these titles don't have any signs on my pressings.