I was shooting on the bus and while I was editing a small batch of photos shot at f3.2 and another small batch shot at f4 I noticed it. Sharpness wasn't the issue, what should have been sharp was sharp, it was the out of focus parts of the photograph that were giving me trouble. I don't even know how to describe what was happening to the soft areas of the photo. It looked like it had been digitized into some form of cartoon and my out of focus background became the optical center of my image. I looked at a very similarly focused photo shot at f4 and there was no issue with my background falling apart like f3.2.
And since I like to post a photo with all my posts on my photo blog:
It snowed today in Colorado.