Nothing that I can tell.

A 1x1 square will contain approximately four(4) tiles at the default max resolutions (1:4m). Unless there is something else going. 

One 16m tile covers a 2x2 mile region, and a 64m tile covers an 8x8 mile region. Since we can't download anything less than a full tile, it is expected that these overlapping tiles will stretch out farther.

If you want more high res data, ask for a bigger region, or better yet, mark some rectangles to define the download, as in this tutorial.

http://www.backcountrynavigator.com/content/view/79/46/