Heyo first time giving this a shot and just wanted to remind everyone else that its a good idea to test your assets! Thats how I caught errors like this:

Happy jammin and good luck crammin ;) Just kidding take it easy and take care of what ya gotta. Excited to see everyone's creations!

This is why I always build a mockup first, then extract the tiles from it.

I did hit this exact issue today when working on tree tiles though. Built a few in a mockup, then tried to just copy paste tiles for corners and what not, and yeah, there was a couple bits where it didn't match over the seam. So it always sneaks in either way! :P