Looking good for 40! I think DB does look a bit younger than him though.
On the personal life topic. Being in the TV/film industries, actors would be aware there is an interest in them & fans wanting to know his height, eye colour, the name of his dog etc should be accepted. Some stars are always in the spotlight, going to high profile events, premieres, the most fashionable clubs & that will create media interest in them. James has chosen to stay away from that lifestyle so isn't so likely to be intruded upon.
In my opinion, fans wondering who he is dating or his age etc shouldn't bother him. If he wants to tell them he can but he's in an industry where he will generate fans and an interest in himself. I'm sure he knows that & it would only be the media that would really bother him.
Also, how tall is he by the way?