Any suggestions you leave with a low score would be much appreciated. What you like about it. What you don't like about it...

did you drawed over your border?, because that seems to be the problem in this tile, i can be worg any way, the landscape is great as a drawing.:)
the checked tile and the tile on the quilt seem diferent, in the border union, so the only explanation i can imagine is, that you drawed a little over your border or smudge over it. is that it?

the clone tool is a newbie thing...then yor edges will go in eachother. just go on practice with it and then use it in your work. If you´re uncertain about your tile go and see the tile tutorial.....nice tile btw...you are a great tiler and I didn´t notice the edges at first, just the beautyful palmtree;)

Keep up with the good work!

what i did was to take the starting image, duplicate that base layer, delete the original locked one, and then erase/delete the black square you're responsible for... just make that border your frame and keep it at the top of the layer stack, then you're free to paint on any layers under it and you won't mess it up and stuff