[OS X Emacs] launching skim automatically?

[John Wickerson]

Hello, 

So I'm writing some LaTeX in Aquamacs, and I press C-c C-c to compile it, and C-c C-c again to preview it. If Skim is already launched, then my pdf is opened in Skim. If Skim is not already launched, however, then my pdf is opened in Preview -- ugh! 

It used to be the case that Skim would launch automatically in this situation -- does anyone know why it isn't anymore? Perhaps I've misconfigured something? 

Thanks, 
John