git log -S not finding all commits?

Hi,

I did:

$ git version
git version 1.6.4.4
$ mkdir a && cd a && git init
$ echo "Free data" > a
$ git add a
$ git commit -m1
$ echo "Free data allocated by other function" > a
$ git commit -a -m2
$ PAGER=cat git log -S'Free' --oneline
2f34241 1

I would expect "git log" to show both 1 and 2 commit, but it prints only 1.

Is it the correct behavior?

-- 
Daniel