This is just another one of those "smart" things that the smart engineers installed as standard equipment in smart cars - smart eh?
It's quite possible that the rain caused the malfunction - it has in my car - ABS and hill hold features were disabled for a short time - happened several times. Just like door locks not functioning then later deciding to work, that will happen with this as well. - all unpredictable, keeping smart drivers on their toes, and smart dealerships happy.
It can't be all bad, can it?