I've never experienced my hedgehogs doing that. I don't think there's any harm in it as long as there's no soap in the water. If you are giving her a full soapy bath I would just have running water going instead of stagnant water. Take a cup and pour water on her back and splash water on her tummy, then rub a tiny bit of soap using your hands or a toothbrush on her fur and quills, then take a cup of clean water and rinse her off. That way she doesn't have a chance to sit there and drink soapy stagnant water.