Yep. Because the *theory* goes:

- This is a poor answer, I will give it a -1
- If they want to rid themselves of the -1's, then they should improve their answer with an edit
- If they edit it, everyone who has previously voted can re-cast their vote
- If they don't edit it, then the original reasoning for your vote still stands

See for more info:

- http://meta.stackoverflow.com/questions/19021/request-change-in-behaviour-vote-too-old-to-be-changed-unless-post-is-edited
- http://meta.stackoverflow.com/questions/6250/vote-too-old-to-be-changed-unless-post-is-edited