Your post was likely deleted because the comment you were responding to was also deleted (likely because it was insubstantial) and your post didn't add anything else to the conversation. I don't see why you're acting so surprised by this.
I guess whenever your post gets deleted because of the comment to which you responded to also got deleted, you personally get a message from the moderators explaining that "the post got deleted because it was a reply to other deleted post", at least this is what I got from grue when my post got deleted in these situations. So I don't think this is the case.