Why does Samsung GS4 pattern lock sometimes change to side-by-side layout?

I have the SGS4 SGH-M919, Android 4.2.2, WickedV8 ROM.

Normally my lock screen looks like this:

Once in a while, my lock screen unexpectedly changes to this side-by-side arrangement:

I have not done anything to cause this change, and I am unable to find a way to change it back to normal other than rebooting the phone. The "pencil" icon does not cause anything to move. If I try long enough, a message will appear that says something like "your security settings prevent changes to the lock screen". I can still unlock the phone, but the small pattern is less convenient.

I do not find anything in Settings that would control the layout of the lock screen. Can anyone explain why this changes and how I could prevent it or change it back to normal without a reboot?