We don't know what it fell into: falling in a sink should be no problem, having to be retrieved from the deep end of a swimming pool would be outside specification. And if it has been damaged previously that's the ingress protection done.
That said, if it is undamaged and was only dropped briefly into shallow water you should make a warranty claim, as it should survive that (though you may need to be persistent: I've heard many tales of phone manufacturers taking the line that if water did get in it must have been your fault...).