Same here. The first few days after the update, there was no auto-mute. Then one fine days, it happened several times and I thought I touched 'mute' accidentally. And for the past 2 days, there was no auto-mute again.
I've seen similar, on-again-off-again behavior with mute on entry. It has to be a bug, or it would behave consistently. FWIW, my vote would be not to have the audio auto-mute on entry.