This was already reported by Click Upvote, but wrongly closed as a duplicate. I found Click Upvote's when I went to report it myself and decided to raise it again when I saw his question had been closed.
If you vote on an answer but right away you retract your vote by clicking the up/downvote icon again, so the image turns back to gray from orange, it should mean that you have no vote on that answer.
However if you later try to go back and upvote/downvote that answer, it says 'Vote too old to be changed', despite the fact that you have at this point no vote cast on the answer.
Note, I have this state for two answers to this question.