This is concerning. If it changes the presentation so much that you would question the speaker design then how can you be confident about the driver alignment, Xover (lobbing perhaps) or speaker dispersion. Perhaps you have hardwood floors and this made the effect more pronounced? Either it indicates something wrong with the speaker design or room acoustic issues - I prefer to think you have room acoustic issues with such a great speaker.
One of my tests of a good speaker/acoustics is consistent sound from a wide variety of positions - standing or seated - left and right - my experience is that good room acoustics and good speaker design means that you can move around without abrupt changes in response/imaging (widest sweetspot = most natural sound). Generally good balanced sound should be achievable anywhere in the room (standing or seating) provided you are at least 3 feet away from a wall and 6 feet from the speakers - image will be most precise in the sweetspot, of course.
One of my tests of a good speaker/acoustics is consistent sound from a wide variety of positions - standing or seated - left and right - my experience is that good room acoustics and good speaker design means that you can move around without abrupt changes in response/imaging (widest sweetspot = most natural sound). Generally good balanced sound should be achievable anywhere in the room (standing or seating) provided you are at least 3 feet away from a wall and 6 feet from the speakers - image will be most precise in the sweetspot, of course.