Minor bug, I know. I'm not sure if this is new or not; I haven't noticed it before, but that doesn't mean it hasn't been like this all along...
Those two labels have the moderator-visible
CSS class applied, while the other labels do not. This is reproducible on multiple sites (I checked Meta, SO, SF, and Gaming -- so probably network-wide) where they all display with the same colour.
Edit, as a response to Rebecca's answer, which she deleted: Since I never noticed this until now, perhaps that feature is too subtle -- maybe a tooltip saying "this field is only visible to you and moderators" would make it more discoverable.