reading an interview with her or something when The Time of Angels/Flesh and Stone came out, and she did say something to the effect of not wanting to flirt as much with Matt Smith because he was so much younger than her and she didn't want River to come off as a cougar. I don't think his Doctor seems that young when he's in character anyway, but it's understandable.
Makes sense, I suppose. But you're right that Matt Smith does a good job of seeming a lot older than he is.
I think it's the clothes. No one under 50 dresses like that ...
Heh. Yeah, that might be it. Only Bill Nye and my Grade 12 English teacher wore bow ties.
Edit: and of course, that he's a good actor. 

soilent brad is PEOPLE!
1 + 2 + 3 + 4 + 5 = EM2C <-- Define it!
"Uh...we don't support the Hannah Montana empire."
- My 6 year old niece
1 + 2 + 3 + 4 + 5 = EM2C <-- Define it!
"Uh...we don't support the Hannah Montana empire."
- My 6 year old niece
/Doctor Who: new trailer
20/01/2011 10:24:10 PM
- 838 Views
The Doctor in America makes me feel patriotic.
20/01/2011 10:33:21 PM
- 632 Views

Re: The Doctor in America makes me feel patriotic.
20/01/2011 10:44:04 PM
- 654 Views

Have we a start date yet? *NM*
21/01/2011 04:05:59 AM
- 443 Views
No, but it is expected to be earlier than the last couple of years
21/01/2011 05:13:07 PM
- 630 Views
Saw this after watching the Christmas Special.
21/01/2011 06:42:20 PM
- 711 Views
Re: Saw this after watching the Christmas Special.
21/01/2011 06:43:51 PM
- 683 Views
Awesome
22/01/2011 08:08:17 PM
- 547 Views

Re: Awesome
22/01/2011 08:09:38 PM
- 595 Views

Thing is...
22/01/2011 08:21:29 PM
- 636 Views
Re: Thing is...
22/01/2011 08:22:38 PM
- 710 Views
Re: Thing is...
22/01/2011 08:44:16 PM
- 698 Views