A quick FYI this morning I ran chkrootkit from a PORTS install on FreeBSD 4.9 this morning. It comes up with a few "INFECTED" files as so:

There were no other errors. To be safe I built and used the GCC Fileutils including gls and again chkrootkit said the same files were infected. A quick web search found a few people having this problem with FreeBSD 5.x but no mention of 4.9. A quick trip to chkrootkit.org and I downloaded and installed the new version and it didn't show the problems. Unfortunately there is no mention of this in the changelog that is a part of the readme other than "small bugs corrected".