The animosity between Hillary and Chertoff goes back to the Clinton administration but I can't for the life of me remember what it was. All I remember is he opposed her on something and she lost. I guess I've tried to make myself believe that Hillary doesn't really exist; that the whole Clinton mess was one big nightmare. Whatever it was, I'm sure that she's delighted that Chertoff is now in a position where she can make his life miserable.
Gosh - when memory fails, check GOOGLE. Chertoff was special counsel for the investigations into Whitewater and Hillary cast the only Senate vote against Chertoff for a federal judgeship later on. She may have had to wait awhile to put her hooks into him again but she managed it.