On the first day of operations, the Downtime, er, Downtown Line broke down (it was called a "temporary disruption"), thereby setting a new record in breaking down. Fortunately, it was a free ride day (free till Jan 1 2014).
There is no evidence that the Downtown Line was unhappy with its working conditions when it broke down on Day 1.
Oddly, when PM took a ride on the line on Saturday, it was working fine. Perhaps PM needs to take our trains more often, so that the trains don't break down for the rest of us.
As my friend WK pointed out, perhaps this disruption only proves that the Downtown Line was not designed to operate for free.