A dozen people have registered with my site, but they don't post any reviews. I'm puzzled. Does anyone have a similar experience? Is it anything to worry about? Thanks.

Update: I have at least 50 users. More sign up every day. No reviews. One user added gibberish (dkjdfdlkjffapodifjds). I had to add moderation. Why would people sign up with no intention of writing a review?
Any other jReviews users having this problem? Thanks.
http://vivaslotsvegas.com/