"kernel" being "out" doesnt mean anything directly to a distribution with a support policy. Instead, the maintainers of your linux distribution (in this case, ubuntu) will backport important changes that are deployed to downstream kernels.
Translation- dont worry about the new kernels. Unless you know why you want it, you dont want it. stick to the supported kernel for your particular linux distro. people tend to succumb to "upgrade-itis" but in practice it usually doesnt provide any utility and often can cause pain.
