If you feel uncomfortable about this trust decision made for you by OS
X, I would suggest taking a peek at the entire set of trusted root
certificates in /System/Library/Keychains/ (note that Keychain Viewer
hides one of them from view by default, so run:
open /System/Library/Keychains/*
from a shell).I don't run OS X anymore, but I was not happy with what I saw at the time.