Is the tissue surrounding the eye (the conjunctiva), swollen and red? Are her eyes red and irritated looking, is she rubbing it at all? This being besides the discharge coming out of her eye.
It could be something as simple as an irriated eye, or allergies.
If you're concerned, I would talk to your vet. That's your best bet, I've got a lot of experiance with this (unfortunately), but your vet is always your #1 option.