It seems that by default, the Dansguardian logrotate entry is not set to compress old logs as they are rotated, and as such they are renamed from "access.log" like so:
Unfortunately, the DG module includes these when analyzing logs and I feel that they should be excluded since they do not END in .log, nor .gz
This is what the DG module shows when run:
Analyzing DansGuardian logfile(s) in /var/log/dansguardian: access.log-20101027, access.log
Optionally, a check box to also include these files could be added to the query set up page for people who prefer to not compress their old,rotated logs.