Git diff-file bug?

Hello. I'm fairly new to git and am witnessing some strange behavior with git that I suspect may be a bug. Can anyone set my mind at rest.

Every so often (I've not quite figured out the exact set of circumstances yet) "git diff-files" shows that every file in my repo is modified, when I expect none to be. If I type "git status" (which shows what I expect - no files modified) and then "git diff-files" again, git now shows that no files have been modified (which is what I expect). It's like "git status" is resetting something that "git diff-files" uses.

I'm trying to figure out what the problem with "git diff-files" is because gitk uses it under the hood, and I think that gitk is reporting erroneous changes (which are also reset by performing a "git status" in the repo) in the "patch" files list.

Any thoughts? I'm using git 1.7.11.4 on SLES 10.3.

Thanks, Scott.