Non-Square Gravatar image sizes get stretched by hard-coded height/width.

An image size of 62x83px will get stretched (i.e., 85x85px). It may be better not to hard-code the width/height of the gravatar.

; gravatar.module:
165 #$variables['picture'] = theme('image', $picture, $alt, $alt, $size, FALSE);
166 $variables['picture'] = theme('image', $picture, $alt, $alt, FALSE, FALSE);