I wouldn't be too concerned as an isolated incident, but it would be better if you could remove the opportunity for her to eat snails and get a taste for them.
We went thro' exactly the same issues with William, it's the nature of pups to test thing out. I still make a tour of our yard before letting William out in the evening and remove all the snails, slugs, and frogs I find, although last night he nearly had a large stag beetle.
There is a lot of talk about Lung worm infection from eating slugs and snails, and I note in my area some vets seem be cashing in on the subject by publishing adverts with dire warnings. My vet laughed at my concern saying he had seen about three cases in his whole career, and although some areas are worse than others,(ours isn't one of them) provided the dog isn't an habitual snail eater the risk is fairly low.
Symptoms of lung worm are coughing, which of course can be related to much more common complaints.
