Hi again mattkime,
If you were using Canon ImageBrowser,
I noticed the comment was not shown in "Preview Mode" in
the browser window, but is shown in "List View", under the image thumbnail, the last line under IMG number,
size, date taken, then (the comment). The image I attached is straight from the camera, but a large file size
one that I downsized with another application had the comment removed.
Edit: Being a Mac user you might have Graphic Converter installed (may need a recent version), if so it also shows the
comment in the Info panel, under "Exif Tool"
Edit 2: Have to retract that bit about Preview mode, after a recheck I see that the comment is shown in the comment box.