I just found the same thing on mine (no joke like 10 sec. earlier), not nearly as many and only on a few (2 per plant) of the bigger fan leaves. My guess is some micro pest got in and is trying to do some damage, but just can't get a grip (at least on my plants). I wasn't going to worry about it and just keep an eye on it, but yours looks like it could be a problem, might just be a nute issue, I got a book and will post after I read it tomorrow