No, as long as you verified with one of her parents that she has pink eye and not just a "pink eye" from allergies. Since she'd already been on the premises for a few hours (vs. standing at the front door), I probably would have called her house to ask the details: "Susie just told me she has pink eye and needs a cold cloth. What's up?" If she said, "Oh, she's not contagious" then you could probe for more info (like, "Why not?) or what meds she'd been on or whether she really needs a cold cloth. If she just wanted attention and her pink eye was 2 weeks ago, that's something else again.
Otherwise, there's no reason she should be in your house or her school, and there's no reason to feel bad about your decision.