From what I heard it may have caused the rotation to slow down but nothing that we will noticed. It has happened before and we didn't noticed it. This time it was a little bigger but they said still nothing we will notice.
Now yes there could be one that will some day change things a little, that is a given. Look at all the stuff the earth has done in the past. It's nothing new that the earth changes and shifts all the time. Nothing to get Chicken Little over!!!
