Yes, the background is a dark green, and yes, some of it is slightly overlapping the smiley face. Also, yes, the top right corner is a slight framing issue. Details, all details. This little smiley is hiding on the side of a shed that is rarely ever seen by human eyes. It can be found somewhere in the labyrinthine alleys of my home city. It is a detail! Details of a large world, bazillions of them, they are what makes the world an interesting place.
Look for the details and you might be pleasantly surprised. Sometimes you will come across something that is sure to make you smile :D
http://robotlizzzrd.deviantart.com/art/Smiley-650079844