Hourly cron jobs running to early

[Spil Oss]

Hi,

A system I manage that was recently upgraded from 9 to 10.0 and to a
later version of VMWare vSphere (5.5U1) is no longer running hourly
jobs at the top of the hour but just before. This is especially
annoying for newsyslog that doesn't then cycle logfiles that are set
to daily rotation.

grep -E " (00|23):" /var/log/cron.log
Jun 25 23:59:34 gw /usr/sbin/cron[94620]: (root) CMD (newsyslog)
Jun 26 00:59:51 gw /usr/sbin/cron[95380]: (root) CMD (newsyslog)
Jun 26 23:59:12 gw /usr/sbin/cron[21259]: (root) CMD (newsyslog)
Jun 27 00:59:34 gw /usr/sbin/cron[22036]: (root) CMD (newsyslog)
Jun 27 23:59:25 gw /usr/sbin/cron[49211]: (root) CMD (newsyslog)
Jun 28 00:59:34 gw /usr/sbin/cron[49968]: (root) CMD (newsyslog)
Jun 28 23:58:55 gw /usr/sbin/cron[83459]: (root) CMD (newsyslog)
Jun 29 00:59:51 gw /usr/sbin/cron[84221]: (root) CMD (newsyslog)
Jun 29 23:59:51 gw /usr/sbin/cron[6571]: (root) CMD (newsyslog)
Jun 30 00:59:51 gw /usr/sbin/cron[7327]: (root) CMD (newsyslog)

ntpd is configured on the server and working fine
# ntpdate -q ntp1.nl.uu.net
server 193.79.237.14, stratum 1, offset -0.000250, delay 0.02942
30 Jun 10:54:50 ntpdate[19771]: adjust time server 193.79.237.14
offset -0.000250 sec

Looking at all hourly newsyslog jobs for a day
14:59:51 15:59:47 16:58:42 17:59:51 18:59:55 19:59:55 20:59:51
21:59:12 22:59:34 23:59:51 23:59:51 23:59:51 00:59:51 01:58:42
02:59:29 03:59:47 04:59:51 05:59:47 06:59:38 07:59:51 08:59:42
09:58:42 10:58:42
I don't really see a pattern in this