Are you sure you got "hit" as you put it? Maybe some other sites are simply out ranking or out classing yours? I have noticed some traffic reductions on one site recently, although it was in the middle of migrating the site at the time and made some mistakes with redirecting the old permalinks, so I am not sure.
But honestly, worrying about Google thinks about my sites is starting to "do my head in" and I think it is easier to please real people than the Google corporation. Social media signals and social media back links as well as old fashioned back links is where it's at, I think.