How Do I Know What I Think Until I See What I Say?

I'm not ready to query my novel yet - I'm in the midst of what I hope will be the final draft - but I thought I would get a jump on hook writing by submitting my hook to the Fangs, Fur & Fey hook contest. The hook will be critiqued by a published author, posted publically for people to comment, and, if it's successful, I'll get to submit pages for critique as well. I just checked my email and got my contest number and, frankly, had a little bit of a freak out, like "STOP! NEVER MIND! GIVE IT BACK!" I'm not sure why this is - I'm not a nervous person. I taught for many years, I've argued in court, I've been in critique groups, I enjoy public speaking. So why does exposing my hook (not even the book itself!) make my stomach quiver? Perhaps because this is the first wide exposure of my idea to the world. Perhaps because this is the internet, where anyone can become a troll and say "this sucks!" Perhaps because I'm a bi