The question was reopened by five community votes. To address what I think is one of your concerns: your vote has not been suppressed or forgotten. It remains viewable in the post's revision history and in its timeline. Both pages are publicly available, even to users who are not logged into the site.
If your comment was automatically posted for you when you voted to close the question, then it was removed when the question was closed, as Oli says. Thus the automatic removal of the comment and the reopening of the question were two separate events, which happened to occur with only a short time window in between.
Even though you probably cannot immediately vote to reclose that question--since you had already voted to do so--you can still manually post a new comment indicating that the questions are related, or even making the case that they should be duplicated once again. If no other comment on the post expresses that information, then I would suggest you consider doing so (even though I was one of the reopen voters, so it is possible I might not personally agree with what you might say).