Many times when I have had this happen it settled fairly quickly when I made sure that the links I had coming directly to the site were established 2.0's or other site. I have found that when the links that come in are coming from new (ish) sites it made the site I was monitoring jump quite a bit. That being said I do believe there is something to the mouse trap theory where the big G is looking for changes to happen on a bounce with the idea it is someone trying to game the system.
As for on-site metrics make sure you are solid and follow your grades to establish a good foundation and to build everything else you are trying to accomplish on that.
Make sure you are linking in with established sites and remember that slow and steady with a good social and citation presence will win the race when it comes to client sites.
With Respect.
