Did you check your SERPs (Search Engine Results Pages) positions? If they change you would see a difference in your organic traffic from Google.
I also noticed that but I don't think that your problem is connected to my problem. I know why my traffic is going down because some of my keywords is not in the top 20 SERP ranking anymore.
I did not notice a change, maybe one of your key-words you ranked high dropped in SERP like 'ssandecki' said