I have had a few panicky, or concerned, or curious, or irate, emails about why some comments go into the moderation.
In answer, most of the time I have no idea why. Sometimes it is because of key words or links in the comments. At other times, the non or newly registered go into the queue. Then there are those users whom I have decided to flag.
Sometimes it takes me a while to approve comments, especially when I am enjoying some down time.