executable script /etc/cron.daily/logrotate has in it, amount other things, the command:
  /usr/sbin/logrotate /etc/logrotate.conf

/etc/logrotate.conf has in it, among other things
  include /etc/logrotate.d

/etc/logrotate.d/syslog-ng has in it, among other things:
  /var/log/remote/*/*.txt
  {
        rotate 8
        maxage 30
        daily
        missingok
        compress
        delaycompress
        postrotate
                invoke-rc.d syslog-ng reload > /dev/null
        endscript
  }

That was set that way yesterday just before noon.

An example directory listing for /var/log/remote/10.128.0.3/log.txt shows only
  drwxr-xr-x  2 root adm      4096 May 26 11:49 ./
  drwxr-xr-x 24 root adm      4096 May 26 23:10 ../
  -rw-r--r--  1 root adm 456943474 May 27 14:55 log.txt

And finally, log.txt in there has lines covering the period:
head -n 2 log.txt && tail -n 2 log.txt
  May 26 11:38:02 10.128.0.3 %ASA-5-304001: 10.134.0.104 Accessed URL 108.168.240.194:http://tags.[snip]
  May 26 11:38:02 10.128.0.3 %ASA-5-304001: 10.134.0.104 Accessed URL 98.139.225.42:http://ads.yahoo[snip]
  May 27 14:56:54 10.128.0.3 %ASA-5-304001: 10.144.0.76 Accessed URL 98.139.199.205:https://98.139.199.205/
  May 27 14:56:54 10.128.0.3 %ASA-5-304001: 10.168.0.62 Accessed URL 23.74.9.136:http://crl.microsoft.[snip]

I would have expected to see log.txt.1, or log.txt.1.gz and log.txt.  The old file should have covered yesterday before lunch through midnight last night and the current file should have been all the stuff starting at midnight last night until the current time.