May be the same reason the ABS & brake light on, have it scanned by a mechanic not parts store that should tell what the problem is for both of your questions. Most likely a wire or connector issue with one of the front wheel speed sensors. This can activate the ABS system and in turn make a growling noise, brake pedal feel any different when this happens?
This is most likely an ABS issue assuming your ABS and brake warning light is on. It could also be suspension related. We could provide you with a complimentary visual inspection and try to assist you resolve this issue.