Is it normal that i have sexual fantasies about my favourite band members?

Recently I've been more obsessed with my favourite band than usual and although I don't find them physically attractive (like, they're not my type physically and they're like a decade older at least) I've found myself having overtly sexual thoughts about them. Like, I keep fantasizing about gang-banging with them and stuff, like a group orgy, even though I wouldn't want that in real life, and even masturbate to it. Is this normal? Even though I wouldn't consider them physically attractive as such but just because of the music they make and everything? And that they're too old for me anyway?