left_ptr-48.png has two transparent vertical lines
whiteglass/left_ptr-48.png
has two vertical transparent lines, as shown here (magnified and with a green background for contrast):
This also seems to affect redglass/left_ptr-48.png
and redglass/right_ptr-48.png
(at least for one of the two lines), but not whiteglass/right_ptr-48.png
.