It looks like spring sickness. The only other time I've seen something like that wasn't spring sickness, it was from a spray. If you haven't sprayed it recently then I would put it down to spring sickness. You can either leave it alone, or give it some soluble fertilizer which may or may not help. Some people cut off those fans to tidy them up so if it bothers you you could try that. The damage happened some time ago and there's not much you can do other than that.
