Is it really that big of a deal if a character we thought was male turned out to be female? If it's true (there's no proof), it's not like the character's personality would suddenly change.
btw, for those curious, the fandom freak-out was due to
this page (Spoiler's Alert) from chapter 19 of Kuroshitsuji. It's gotten some fans to start thinking that a hawt male is a hawt female.