See this cropped screenshot:

The font is white on transparent background. So in this exemple we can expect to see 'nothing', not added edges.
I've even "cleaned" the alpha before to be 200% sure it's only 0 and 100% and no other value, each char is a textured quad.

Update: it's not only in PShape, but in any resized image (in my case it was used as a texture). Same when using image(img,x,y,width,height). In my case I have a scale factor of 2.

Update2: As far as I've understand Image() are shapes in the end

@codeanticode any idea on where I can digg to try to help more ? :)