Evidently the asker of the question made a lot of edits, and inadvertently turned it into a "community wiki" question. That means my answer was also marked community wiki. That just doesn't seem right.
This is apparently an undocumented feature with very poor warning for the souls exposed to it.
I posted over at the Formatting Sandbox to see if my answer would become a community wiki. When I clicked "add answer" I got the following message:
Now you didn't get one of these because you are the only answer on that question (for questions with lots of answers, it seems you have to click the 'Add an Answer' button and get the above warning). Instead you got an answer box that looks like this:
Note something missing? This is what a normal question looks like:
In this case, the original post was converted to a community wiki prior to you answering:
The revision that made it CW was at 3:36:09 zulu time.
Your answer rolled in at 4:13:13 zulu time
Since there is no warning, and you didn't realize that the CW box wasn't there, you were unaware that your answer would be automatically wiki-ed
It would be much friendlier if you either got a warning (as you do when there are many answers, though including a warning that your post will automatically be community wiki'd), or at least if it kept the community wiki checkbox and just locked it (any click bringing up a nice little box saying, "Answers to community wiki posts are automatically created as community wikis") or the sort. But that would be a separate feature-request.
You saw before posting the answer the question turned into Community Wiki so you knew the "risk" of not getting reputation for it.
So if you post just for reputation, don't answer questions marked as Community Wiki.
Your answer is CW because the question was CW at the time of posting, that's how things work. I don't see any reason to change this and if the answer is really great, you can still earn reputation from bounties. (I sometimes reward good answers with a bounty so pretty sure others also do this)
Last but not least, the question itself became CW due to many edits. If you think those edits are all justified and not made just to bump with minor changes feel free to flag and ask to undo the CW status of the question. Not 100% sure it will also undo your answer status, but then you can ask for it.