tileSprite seams visible when using atlas and webgl

[Noid]

I'm loading a tileSprite to use as a background like this:
 

this.bg = this.game.add.tileSprite(0, 0, 800, 600, 'pichon_atlas' ,'background2');

 
When Phaser is using WebGL to render and I load an image from an atlas I can see a 1px seam where the texture loops.

It doesn't happen when using CANVAS or when using WebGL and loading the image directly from a file.

 

The image itself has crisp borders without any semitransparent pixels, both as a single file and in the atlas. 

 

Do I need to use separate image files for tilesprites when using WebGL?