Low grade through GameStop not sure why?

Will post more pictures once the card is ready for pickup in store. First time submitting to PSA (I went through GameStop) I got an email confirming my grades are ready to view and all 13 cards got a 9 or 10 except this card. All cards were sleeved immediately when opened from the pack and this card only seems to have a little whitening on 2 corners based off the PSA photos. Will check it out in more detail once I receive the card back, but how hard is it for a pack fresh card to receive a PSA 4 and do you know what might have caused this?