I thought same thing. I retook it a few times, made sure the lens was clean as well. This was against a flat wall so it's not like it could have locked onto something at a different distance by mistake either.

The first one I took with iphone was even worse, but I noticed I somehow got a smudge print on the lens (really easy to do with iphone)

http://pi.pe/mcy6pq -- first attempt
http://pi.pe/c7dl1q -- best attempt