Yeah, that was the VS200, I did it quite a few times the first week I had it, since then, its only happened a couple of times to me. I think this past week, its happened once. It's just how I press the button (I think).
If it does it, then its a problem, its not you or the way you're pushing it. I just went to the VS store and had mine replaced. It took a while to replicate the issue at the store but when they found it they replaced it no questions. My new one has yet to have the fire/locking issue.