Beach House

I view this photo as a play of parallel lines. What I found

interesting is that even after I straightened the roof, the

horizontal lines of the window frame and the stairs were not parallel

to each other and to the frame of the photo. Is it due to the lens I

used (Canon EF-S 17-85mm IS USM) or was my own position off centre?

Thanks for your input on this and critique in general.