Yeah, there's always a risk of someone discovering your most intimate thoughts and feelings. You might also feel more secure if you buy a lockbox as well for it.

Another thing you might do is this: Create a "decoy" journal. Write stuff in it each day, like you do with your real journal, but keep the content to things that won't give people anything to use against you. Make up stuff, be creative. Have fun! You don't have to lock this one up, but hide it, so it looks like it's something you didn't want found. If someone finds it, they will think that's your real journal, and not bother looking for your real one! :-)