This question already has an answer here:
It's really frustrating when you post a new question, and a person down votes it and then they close the tab. The OP can add a comment such as "Why down vote?", the post would still be down voted even though the OP fixed the issue making the down vote invalid. Then it would still be -1, unless someone up votes the post (but then this gets tricky: the up voter just wanted to fix the -1, not necessarily up vote it and give rep). So a solution: subscribe the down voter to the question, no?
That'd mean he would get notifications when OP's post is edited or new comments on the question or comment.