serverStatus().indexCounters not updating properly

The documentation says that the values in db.serverStatus().indexCounters should be updated each time an operation uses an index: http://docs.mongodb.org/manual/reference/command/serverStatus/#indexcounters

This is not happening. I tried creating a simple collection and performed a find() query on it, with and without an index. If the above is correct, at least the "accesses" counter should have been updated, but it doesn't change in either case.

The behavior is the same in both 2.4.9 and 2.6.1.