Evil, Aquamacs, ctrl-w, and undo

Hello, I've been bitten by this several times, and I'm wondering if this is a bug or if it's something I'm doing wrong. I'm writing some text, in insert mode, and I want to go to the next window. So I hit "ctrl-w ctrl-w", and it deletes to words as I forgot to get out of insert mode. The problem is I cannot undo this: if I get to normal mode and do "u", I get back further in the history. If I do a redo (ctrl-r), I cannot get the words back. (I also tried doing "cmd-z" without leaving insert mode, and the problem is the same.) Looking at the key description, it's bound to "aquamacs-backward-kill-word". I'm going to try to unbind it, but I'm wondering if the fact that I cannot undo this action is a bug. Thanks, Alan