This message is issued by the kernel when it mounts a file system that's marked as clean, but whose "number of mounts since check" counter has reached the predefined value. The solution is to get the latest version of the ext2fs utilities (e2fsprogs-0.5b.tar.gz at the time of writing) from the usual sites. ("Where Are the Linux FTP Archives?")

The maximal number of mounts value can be examined and changed using the tune2fs program from this package.