They've mentioned little things-
-In the first episode of the new season, Grissom found a tape of the main guy who took Nick and put him in the grave. It was an audio tape, and on it you can hear the guy talking to someone else, meaning he had an accomplice. They don't know who the accomplice is yet, and Nick doesn't know about the tape.
-Also in teh first episode, a bug fell on Nick and he freaked out.
-In the episode about the cult, Nick had trouble going underground.
Thanks for the banners and avi Christina!