Yesterday I was taking some pictures with my 12-40 mm Pro and noticed some strange blurry effect as visible on the pictures below. On the first picture you can see it in the bottom left side. And the second picture is a crop from a left side of a picture. They were both taken at f/2.8, ISO 200 and 1/500 and 1/640. It kinda looks like bokeh, but on the first picture, the bokeh on the right side looks a lot different. Is this caused by a decentered lens perhaps? I took several other pictures and didn't notice anything similar again and this is also the first time I've seen this since owning the lens for about 10 months now.