The gemara says that Miriam said a nevuah predicting Moshe's birth, but when he was put in a basket and placed in the river they thought it was all over so Amram gave her a slap on the face saying "what happened to your nevuah?". Why such an aggressive response?
Perhaps this can be explained based in a principal of the Rambam that the meshech chochma uses often to explain various pesukim. The Rambam writes that when a navi says a positive nevuah, it will be fulfilled even if the jews do aveiros (because otherwise it will be impossible to test to determine if a navi is a navi emes or navi sheker), but a negative nevuah can alway change with teshuva. Amram thought that when moshe was being thrown in, he would not survive. Since a positive nevuah cannot change, this would indicate that miriam was a neviah sheker. The aggressive response was because moshe being placed in the river indicated retroactively that what miriam was claiming to say b'navuah was not navuah at all and therefore indicated that she was a neviah sheker.