yeah light leaks can cause that or growing outdoors i find can also cause it sometimes i grow indoor with a timer so i haven't had it happen too many times like once i believe. i run an 18/6 light schedule for veg and a 12/12 for flower
if they are light almost white or beige is pre mature. black seeds are moldy or have been kept wrong. green ones are also premature but i find they have like a 25% chance to work out still. hope this helped. happy growing.