I think that after editing a post, the vote is no longer locked (even after a grace-period).
Assuming that I've got the "edit everything" privilege, I upvote a post. I try to unupvote it after 5 mins. I can't do it as it is "locked". Now, I revise the post (a valid and substantial revision only), allowing me to undo the vote. Then I upvote the post (say, after some time - 15 mins). Seeing the post after several hours, my vote should be locked. However, it isn't locked and I can toggle between upvote, unupvote, downvote, etc.. whenever I wish.
Isn't there some grace period? How long I'm allowed to change my vote?
An example: Today, I revised an upvoted (by me) post: Can we have a black hole without a singularity? (I just added a tag and changed the HTML to SE's standard linking style). Then, I undid my vote. After a while, I re-upvoted it. Now, I can toggle my vote freely, from upvoted, to no vote, to downvoted. Is this limited only to the editor or can others now vote freely as well?
For some background information, see the H-bar chat link where I've discussed this issue with a friend: http://chat.stackexchange.com/transcript/message/7459118#7459118 (Please read all the messages that follow).
Is this by design or a bug?