I recently upvoted an answer to one of my questions. The answer was wrong, but I thought it was helpful enough to earn an upvote.
A couple of hours later, the answer changed significantly and (in my view) got a little worse. The answer was still wrong and had earned 4 upvotes. So I decided to un-upvote.
Seemingly as a result, the answer's vote count changed by -2. This raises a question.
Was the -2 change due to my own upvote being removed and a downvote being logged? This was not my intention. I believe this is the case because (1) the downarrow now glows on my view and (2) it says under "reputation" that I received -1 for downvoting this question.
Why can't I just undo an upvote? edit: I can, but didn't know how; thank you for the remedy mentioned in the comments.