Don't know if it'll help,but in case you want to find out wether it is a
reflection or not,one thing you could do is:place another object,a plant
or so,on the roof on the right hand side of the windows so that it would
be covered by the gable windows when rendered.If you can still see it
through the windows you'll know it's not a reflection and that you'll have
to fix either the house model or the shaders.
Hope it's not too confusing.