This is covering the exact issue I'm dealing with. I commented out the same code around "fix_age" and had some success, but not as much as you ... have a look here: http://arduino.cc/forum/index.php/topic,81175.msg612786.html#msg612786
I figured "fix_age" wasn't working, so commented it out, but now I'm getting same time reported every time it starts (7:37:12 8 Jan 2000 from memory). I know the GPS is working as I've got another program that reads from it just fine, so I'm pretty sure the problem is in the way I'm using timeGPS, or with timeGPS itself.
I'd really like to nail this one ...!
PS: you say it took a while before you got synch ... can you estimate how long that was (a few secs, or mins or longer?)