[Allen Rowell]

When you do certain kinds of cuts it can result in a sliver of audio being created. When you zoom all the way in, you can see what looks like a single frame. That is the click. I think it happens when you try to drop in a new clip but instead of the new clip dropping between two clips it actually makes a cut in the tail or head of one of the clips leaving a sliver behind. I have not isolated what exact settings and workflow causes this. It may have to do with the fact that audio can be cut on a sub-farme level as compared to video. You should be able to delete the sliver.