excellent point about md5 to check the file. beware that my hack will certainly fail on log files that are being rotated with the same name (like simple access_log) - it depends on the logfile names to be unique (like with date). I fire all my apache logs through rsyslog to a central log server and name the resulting log files with the date:
$Template apachelog,"/srv/syslog/www/%syslogtag:8:50%/%syslogtag:8:50%.%$YEAR%%$MONTH%%$DAY%.access_log"
$Template apacheformat,"%msg:2:$:drop-last-lf%\r\n"