Abby's dress. I think that was one of Kate's still in their closet. And Abby's face during that scene reminded me of 'Kill Ari pt. 1' when she had been crying and had no makeup on. Sad memories. But my theory is that Abby is making faces at Ziva because the new girl is the replacement for Kate. And did someone say it had been a hard few months (McGee, perhaps)? One of my friends said someone had, but I missed it. If that's the case, Abby seems to be the only one still mourning (she even said that she still was), indicating a deeper relationship than any of the others.