Evidently, the new LJ setup has a weird loophole that enables your locked entries to be found via a search if you have not opted your journal out of searches. And chances are, you have not.
-From the navigation strip, click on Account
-Select "Viewing Options", under Site
-Scroll down past Viewing Options to Additional Privacy Options
-Make sure Search Inclusion IS CHECKED
-Make sure Explore Area Exclusion IS CHECKED
I had one of those two checked; I've now checked both. I don't lock much of my journal, but this is a good precaution.