As mentioned he's 67, so it's not like he looks older than his age suggests. But if you compare the 2006 to the 2012 pictures, you can see that he did age a lot in a short space of time. It's as if he was defying his age for a long time, but it eventually caught up with him.
I always thought he looked immediately older after he shaved his head and then grew it in shorter than before. Not sure if he just can't have a full head of hair anymore, or he just went with a different shorter style, but I'd argue that if he still had all his (albeit) gray hair he wouldn't "appear" his age. JMO.