UPDATE: It looks like my 13.0.1 is calling code from this diffed CharMatcher.
http://code.google.com/p/guava-libraries/source/diff?spec=svn69ad96b719d7cd3d872a948d7454f1
I just ran the exact benchmark you provided, and got
took 74 ms 2nd took 0 ms
took 74 ms
2nd took 0 ms
...Perhaps the problem is on Eclipse's end? Are you running in debug mode?