Apparently in this afternoon's game between Sweden and Norway there was a problem with at least one of the rocks (more specifically with the batteries in the hog-line-violation detection mechanisms) in one of the early ends. Unfortunately I was unable to be here for the entire draw, and I missed what happened.
But during the media scrum after the game, which Norway won 8-5, Edin (skip, Sweden) was very polite and very gentlemanly about the entire situation. He did make it clear that he thought the rocks should have been replaced with slightly different angles, and he made it clear he thought his team would have had a much better chance of winning had the error not occurred. Yet at the same time, he also acknowledged that it was up to his team to overcome the situation and make good shots.
It seems to me it has been quite awhile since there have been problems like this. I expect the folks in charge of the rocks will want to take additional precautions in the future if, indeed, Edin's assertion is correct that the batteries were dead in several of the rocks.
[Update]. Folks on the media bench tell me that the malfunction was that BOTH the red and the green lights came on for a Swedish rock. As a result, the sweepers and players weren't sure what to do, so they didn't sweep. When it was discovered there had been no hogline violation, it might have been reasonable to replay the shot. Unfortunately that rock had moved a few rocks in the house, and the two teams couldn't agree on where to replace them. Edin was certain he knew where they belonged, but in his words "the other team wasn't quite sure and hadn't been watching so carefully." So they replayed the entire end.