[logback-user] TimeBasedRollingPolicy failed to rollover logfiles yesterday, but I see no RolloverFailure?

[Robert Kuhar]

I have an appender configured like...

<appender name="DAILY_ROLLING"
class="ch.qos.logback.core.rolling.RollingFileAppender">
  <File>logs/dm.log</File>
  <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
    <FileNamePattern>logs/dm.%d{yyyyMMdd}.log</FileNamePattern>
  </rollingPolicy>
  <encoder>
    <pattern>%m%n</pattern>
  </encoder>
</appender>
...
<root level="info">
  <appender-ref ref="DAILY_ROLLING" />
  <appender-ref ref="SYSLOG" />
</root>

...which typically has the effect of logging current data to the
dm.log file and everyday at midnight rolling over the dm.log into a
file named for the date, dm.20130205.log. Yesterday, however, for the
first time ever, this rollover did not occur on any of my production
servers. My dm.log file now has 2 days worth of data and I am
wondering what went wrong? I expected to find a RolloverFailure or
some indication of what went wrong to be laying in the dm.log file but
there is nothing there.

I have never seen this mechanism fail in either logback or log4j and
am at a loss as to where to start troubleshooting.

Where do I look to figure out what went wrong in logback?

Am I correct in expecting some
ch.qos.logback.core.rolling.RolloverFailure stacktrace to be appearing
in my dm.log file or does it only go there if my app is correctly
catching and logging all throwables?