Kamala apologizes for saying 'well said' after man called Trump's actions 'Mentally Retarded'

Some guy was asking Kamala Harris a question and he referred to Trump's actions as "mentally retarded." Kamala Harris told him, "well said, well said" and then later apologized. She claimed she didn't hear what the guy said, even though he had a microphone and people laughed at clapped after he said it. How did she not hear the guy with the microphone? And is she lying again with her fake apology?
If there's one thing I know about Kamala Harris, it's... (I'll let you finish this one in the comments).