I just logged in after about a month or so break and the key I used to use for gaining altitude on flying mounts (SPACE) no longer seems to work. It still kinda works if I hold it down, but the moment I stop my toon plummets straight down. To my knowledge, I have not remapped any keys.
Just remember to fly over enemy toons when your mount has to "relieve" itself. Will teach them to use umbrellas more (and invest in anti-flying weaponry, too, for when the dragons come back!)