Strange behaviour in logging files and log rotatation, hopefully an easy answer?

[Bob Brennan]

I host some relatively steady volume virtual domains and in order to
keep the log access files to a reasonable size I logrotate them once
every night and only keep 10 days worth. The logrotate works fine with
typically
  access_log
  access_log.1
  access_log.2
  .3 .4 .5 etc
happening as expected, the problem is that only one of those files
receives the log information, even as it's name changes! So typically
access_log.1, .2, .3 for instance are all 0b while .4 continues to
grow into the megabytes until it is deleted.

Before blaming it on my configuration twiddles or virtual sites let me
note that I have an up2dated FC3 server install and in /var/log I note
that logs files I have never done anything with, such as up2date,
xferlog, and spooler exhibit the same problem whereas boot.log, cron,
maillog, and messages all have sequential and full files with the .1
.2 .3 extensions, behaving as I would expect. These files all have
default FC3 logrotates.

As test I renamed a troublesome "access_log.3" to "rubbish" and
accessed the site, the access was logged to "rubbish" while a file
called "access_log" in the same directory stays at 0b.

Obviously a feature I don't know about is tracking the file being
written to even though it's been renamed. I doubt it's a lock problem
because more than half the log files exhibit it all the time and few
are updated frequently enough to cause a race condition, but I'm open
to suggestions.

Any help/pointers/ideas greatly appreciated, I can't even think what to google.

bob