Hey Brad,
By default, Blender uses the center of the 3D Viewport for zooming. If you zoom out (objects getting smaller), everything moves towards the center. Pressing the Home key, centers your Objects and then zooming works as you expect (only in Z-Axis, when in Top View).
You can also set Blender to use your mouse position as reference point for zooming: Preferences > Navigation > Zoom > Zoom to Mouse Position.
