[Q] How do I prevent USB file access at lockscreen? topic

In previous versions of Android, when I plugged my Nexus 5 into my computer, if it were at the lockscreen I had to unlock it before it would show me the files on the sdcard. Now, though, running 4.4.2, I notice I no longer have to do that. I can just plug it in and at the lockscreen go to my files. While convenient, especially for transferring large files, I'd rather a thief not be able to do this. I can't find any setting for it though. Any ideas?