The nasty looking spot in the center of the scar was caused by a small water blister that formed, apparently as a reaction to the cutting. Even though it's rosy around it, my doctor says he doesn't think it's an infection but to keep an eye on it.
Now I have to make up a good story for what the scar is from. The medical assistant who removed the stitches suggested "a shark bite while surfing at Santa Cruz." I like that. The only problem is the doc did such a neat job on me the scar will probably just fade away.