trailing whitespace problem

when I use git commit -a, I get the following message:

*
* You have some suspicious patch lines:
*
* In src/test.c
* trailing whitespace (line 60)
src/test.c:60: }

when I fix the whitespace problem,  and do "git commit -a" again,
I still get the same message.

Only after adding the file again, with "git add src/test.c",
I can commit my changes.

git version 1.5.3.2 (on cygwin)

ps: not related to CR/LF...