No reason to be scared.

Ask a few additional questions. If the seller is honest, they will actually welcome questions. If the seller gets snippy...well, listen to your gut.

If you can afford her, just house her in a different room for now and if you handle or clean any of your snakes/enclosures, just make sure you do her last. Or if you messed with her, wash and change before you mess with the others.

Quarantine is really not that difficult to do. And its only for a few weeks. Or at least until after a few good meals, poops and at least one good shed.