In 7684 I started to experience blocks of folded code expanding on their own. I found http://www.jetbrains.net/jira/browse/IDEA-16940 from a few weeks ago against 7657. It reported this happening when an opening brace was typed. I am however experiencing the issue at other times. Even at time when I am not actively typing anything.
I added a comment to IDEA-16940, but was curious if anyone else is experiencing this.