Eu diria que você está executando 12.04.5 e é a pilha de ativação de hardware que foi introduzido há alguns meses atrás. Algumas partes relevantes do link:
What is HWE?
Hardware Enablement Stacks (HWE) are incorporated into installers for select Ubuntu LTS (Long Term Support) point releases. It is a special Ubuntu feature that provides an LTS release with hardware support introduced in newer Ubuntu releases. For Ubuntu 12.04 the point releases are .2/.3/.4/.5 and the corresponding Ubuntu releases are 12.10/13.04/13.10/14.04.
The HWE path can be obtained in 2 ways:
- Installing Ubuntu from the media (ISO) for these point releases (where HWE is used by default)
- Manually installing some packages
End-of-life (EOL) for 12.04, 12.04.1, and 12.04.5 HWE is April 2017 but for the other HWE stacks it is roughly when 14.04.1 is released: Aug 8, 2014.
And why should I care?*
Starting Aug 8, 2014 systems running 12.04.2 HWE, 12.04.3 HWE, or 12.04.4 HWE will no longer receive software updates for the kernel and, if you're running it, the graphics stack.