boost::mutex::scoped_lock conventions

Is there a convention about whether or not to explicitly call .unlock()? In the case where everything to the end of the scope should be locked, there is no NEED to do it, but isn't it a bit sloppy to leave locks locked? Much like not using braces on one-line 'if' statements, it could cause maintenance problems later. What's the current thinking? Thanks, - Mark P.S. I'm currently always unlocking, because sometimes I want to unlock before the scope ends. This makes it clear exactly what I intend.