Can newborn choke from mucus in sleep?

I have a 9 week old girl. She has been getting snotty at night: snorting, snoring, etc. A couple of times I have gotten her up in the morning and she spits up a good bit of clear mucus. The Dr. says this is normal. Last night she really scared my wife. I wasn't home so she kept her in the bed (I know not everyone likes this but that isn't the discussion here). Anyhow, my wife woke up with the baby bright red, arching her back and flailing her arms. She couldn't breath and was choking on the mucus. Absolutely no breathing at all. When she picked her up she projectile puked mucus again. Should I be worried or does this happen all the time when they are in their own bed and we just never see it?