Service stats stopped on xxx.xxx.net

[todd_dsm]

Release 5.0.16_GA_2921.RHEL5_64_20090429021719 CentOS5_64 NETWORK edition

# cat /opt/zimbra/zmstat/zmstat.out
sh: /tmp/mysql.out.6308: Permission denied
09/08/2009 21:33:00: Error while running '/opt/zimbra/bin/mysql --user=zimbra --password=xxxxxxxxxxx --database=zimbra --batch --skip-column-names'. at /opt/zimbra/zimbramon/lib/Zimbra/DB/DB.pm line 73, <OUTPUT> line 5148573.

sh: /tmp/mysql.out.6308: Permission denied
09/08/2009 21:33:30: Error while running '/opt/zimbra/bin/mysql --user=zimbra --password=xxxxxxxxxxx --database=zimbra --batch --skip-column-names'. at /opt/zimbra/zimbramon/lib/Zimbra/DB/DB.pm line 73, <OUTPUT> line 5148573.

sh: /tmp/mysql.out.6308: Permission denied
09/08/2009 21:34:00: Error while running '/opt/zimbra/bin/mysql --user=zimbra --password=xxxxxxxxxxx  --database=zimbra --batch --skip-column-names'. at /opt/zimbra/zimbramon/lib/Zimbra/DB/DB.pm line 73, <OUTPUT> line 5148573.

sh: /tmp/mysql.out.6308: Permission denied
No iostat installed on this host at /opt/zimbra/libexec/zmstat-io line 30.
No iostat installed on this host at /opt/zimbra/libexec/zmstat-io line 30.
/opt/zimbra/zmstat/mysql.csv was stale (2009-09-08) pre-rotating
Warning: Not possible to monitor process stats

I was able to restart the server (zmcontrol stop && zmcontrol start). The problem disappeared after that. I'd be interested in root cause theories. Is anyone else seeing this?