I think sometimes it's a case of your body knowing what it's doing a bit more the second time around.
I had leaky nipples the first time I was pg and a huge over supply of milk after Sean was born. The second time around I didn't leak during pg and my milk supply was spot on.
It's not an indicator of how successful BFing will be, don't worry!

PS, I'm not leaking at all this time either!

Bec, yep, that'd be colostrum.