I had a drop in traffic starting around 3/10. I posted about it in another thread on affiliate links because I wondered if that was the cause in my particular case (which I think is unlikely but possible). My traffic had been pretty steadily increasing for many months. I had a number 2 result for a competitive phrase for many months which dropped to number 3 on Saturday along with some other slight drops.
Today I am seeing some flux in this category. I can't tell if it is reverting to an older list, but I see some distinctly different results throughout the day.
Because my category had been fairly stable for many months, I suspect something unique is going on today. Whatever hit me Saturday could be a part of this - or not.