Snap Regions not equal

Hi all. Somehow my left & right snap regions are no longer equal... the left side is slightly larger than the right. This happens whether I drag-to-snap, or use triggers.

Any idea how this happened, or how I can return them to the default 50/50 sizes?


UPDATE: Resolved.

I feel dumb. I'd moved my MacOS dock to the left edge of the screen, which offset the center line between the snapped windows. All is good in the hood.