Is there a reason why my girl friend Wilson W6 strung with Wilson NXT 16, feels noticeably heavier then my APDC strung with PHT17? Both I and her have noticed it. Both rackets were purchased at factory authorized dealers so I doubt that either are fake. But the strung weight of APDC is supposed to be 11.3 ounces and the W6 10.5 ounces. Would the different string size and type account for this noticeable difference in weight?