Whoa I.......don't know why that happened!  I think the issue is that one section of the Verdugo Mountains Landuse=Scrub area was flimsily connected to the rest of it over a road, and I separated them when I created my new area which is adjacent to the sketchy one. 
 Once I saw that the sketchy area still became highlighted when I selected the Verdugo Mountains area, I was going to make the sketchy one into its own area...but then I said "nah better not mess with it in case you screw something up".  Guess that'll teach me to always mess with everything!  Haha.  I'm gonna take a quick swing at fixing it but if it doesn't work and you can merge them that would be fantastic.  I'll report back!