Have you checked your origin and image points for each sprite? Also check the size of the tiled images?
Otherwise, it's a problem with C2 and I can only think of 2 solutions.
1) Make the tiled images 1 pixel taller and wider, then overlap them. If you make the grid width and height 1 pixel smaller than the tiles, C2 will overlap the sprites for you if you have "snap to grid" enabled.
2) Add a tiled background behind the sprites so that the gap blends and isn't as obvious.