I had exactly the same reaction to the Dumbledore thing! He always read as bisexual, to me.

Truth to tell, I actually -- and I've never admitted this before, because I'm still a little embarassed by it -- had this moment the very first time I read The Importance of Being Earnest, with the "Bunbury" scene. I was nine years old and knew nothing at all about Oscar Wilde's personal life or other work.