Does anyone ellse do this?

Over the past 6 months or so I have notist a fononamum in my self that has been growing steadely worse. As I read fiction books, I adapt them into screenplays in my head. I know most people who enjoy reading fiction picture what's happening in their heads, but this is more extreme then that. For everything I read these days, at some point in the prosess of reading I put the book into one of two catagrees: whether it would adapt well onto screen or not. I don't enjoy reading them more or less depending on the catagry, and even if I decied that the stories not sutable for the medium I map it out anyway. I pause to work out camera angles and shot sequances, and if I don't like what I've come up with I'll often re-read a passage to get it right. I'll make dessiciens about what scenes should be cut and added, I'll come up with motiefs and colour scemes, I'll plan out sets that would be needed. Accationally, I'll even make estamates on things like length and cost. I'll also decide what places could be shot in a studio and which should be on location. There's been a couple of books which i've gone through with paper clips to restructure in a way that would work in a movie. The thing that hit me most about this was about a week ago when I realised that I'd just stoped for about six minutes in the middle of a page trying to think up a good musicel theme for the passage I was reading. (I couldn't continue intill I came up with one. I did.) I just want to know if this is in any way normal. So, does anyone ellse do this?