Thanks but I found the problem, while waiting for an answer. I had selected landscape, while at the same time selecting the 24x30 paper size and I guess it just tried to compensate.
Just to say, Qimage just does not do stretching or distortion at all
It will fit an image into the paper's printable area and size accordingly - and tell you! - but never distort by stretching in one direction only.
If you did not discover the real problem and can repeat it it is probably a driver problem and worth sorting out for the future, with the help of Fred's advice of course.
Terry.