It's very likely that several previous and middle comments were deleted, so while based on the comment content they currently look to be in an incorrect order, comments are always shown on the order that were posted, older first, newer last, in this case and considering the mentioned criteria the order is correct.
So there, is no bug.
Update the question.
Comments are, by their nature, impermanent. They're supposed to be used to ask for clarification from the author and to otherwise coordinate improving the question. (The same goes for answers.) Once they've completed that task comments may (and should) be deleted.
If, of course, someone posts a comment that gives you the solution, you ...
You are up-voting an anonymous user with your username because you registered with Web Applications (2013-06-10 13:05:19Z) after the migration (2013-06-10 13:00:52Z).
Comments aren't given the same priority for user association during migration 
He actually posted an answer - then a moderator converted it to a comment.
This isn't especially common, but it is an option for cases where an answer turns out to be particularly useful as a comment (but isn't in any way an answer).
You can take as much time as you need to write your comment. However, once you've saved it, you only have a 5-minute window by which you can edit it. This allows you to fix a typo you've spotted right after you've saved it, but doesn't allow for changing the content of a comment later on, when there may have been a response.
Traffic is pretty light here, so ...