I say "followed" in the past tense because I just blocked him.
Unfortunately, I didn't realize until this morning that I could block a follower, so all of you have been forced to stare at the aforementioned profile pic whenever you came for a visit. Sorry about that.

I actually wrote to the follower in question and told him I'd gladly un-block him if he changed the image, but I kind of doubt that's going to happen.
Anyway, there you have it. Hopefully it won't happen again. If it does, though, I'll block the follower so fast it'll make his or her head spin!