Cheggers the pink plop from space

Here's a game I've been creating just as a test. It's using open-source graphics from the open bundle so there's nothing groundbreaking about the graphics tbh. So don't judge me, I'm only doing this project to learn tbh.

Here's the game in Scirra arcade

Here's the capx

One thing I noticed though is that it looks absolutely fine on my local, running in a browser (Chrome), but when I added it to the arcade, you can see a gap between each graphics block, which is pretty weird. I'm pretty sure I'm seeing it at 1:1 on my local, so no idea why it looks different on the arcade.

Anyone know why this would be?

Here's a screenshot of how it looks on mine vs the arcade. <img src="http://i.imgur.com/vlX4u5Y.jpg" border="0">