duckling keeps one eye closed

[korme5]

Hey guys so today I picked up 2 day old ducklings from a breeder, I have been handling them and have noticed that one likes to keep one eye closed. If I pick it up or anything it opens the eye up to normal but once she settles the eye closes. The eye isn't weeping, swollen, red or hot but she does seem a little more sleepy then the other. Although she has tried to climb out of her brooder a bit should I just leave it and see? Could it just be she is tired and young ?? Any ideas or inputs would be great