I'd not risk it.Just because she doesn't die immediately or get seriously ill doesn't mean it is safe.You need to use completely safe cork meaning that which has definitely not been treated with any sort of chemicals(as cork stoppers may have,you shouldn't ever use them for any pet)and is properly sterilized(frozen for several days to a week before usage,for example).
Consider that just because something doesn't cause harm immediately doesn't mean it is good or safe
For example,a hamster could certainly eat a tiny bit of garlic or leek(known to be toxic)without dying immediately.Or,a hamster could eat a tiny bit of food containing BHA/BHT/ethoxyquin(label regulations in the UK and other places can be a loophole with unspecified preservatives,if it says E&C approved in the UK it legally could be one of these,most likely there is something similar elsewhere)without immediately getting cancer despite these preservatives being known to cause cancer.Does this mean they're healthy or even safe?Absolutely not!