She's probably fine, though she may not be able to avoid predators that well so you should watch her while she's outside. Make sure what you feed them can be fed to ducks as they need different things from chickens. Niacin is one thing, most chick food lacks the amount of niacin ducklings need to help their legs develop properly. I feed mine a mix of chick starter and game bird feed. Let me know how both ducklings do and upload pics if you can, I love seeing those fluffy little faces!