Don't panic! Author scores and individual hub scores vary widely from day today, even hour to hour.
Give it a few week or so before you get too concerned. If the score of a hub continues to drop, try visiting the forum topic "Extreme Hub Makeover" for some advice on that specific hub. I did that a while back and turned one of my "dogs" into one of my most visited hubs!
And also know that Hub score has no importance outside of HubPages! It doesn't influence Google search results or Adsense earnings or any thing else...
Same goes for Author score - irrelevant outside of HubPages!
I hope that helps - I enjoy reading your hubs and think you are a fine writer! Don't let the scores get you down. Just keep writing good hubs and it will work itself out over time :D