UI Sprite location changes its appearance.

I created a .png which has white edges and a transparent body which acts as a border for all my UI elements, but I've noticed that the border of each element seems to vary in regards to edge thickness. See attachments for an examples.

As I move an element around the screen, the entire border seems to change (notice in the attachments how the top edge has a different thickness). These are just simple UI elements on a Screen Space Canvas.

The .png when opened up in any program clearly has evenly sized border edges, so this is something happening with Unity.

Thanks.