I called my midwife that day and she said sleeping was fine too. It's when they become lethargic and difficult to wake is when there's a problem. She was also eating fine and peeing so all was well. I'm paranoid with this one for some reason!
Sleeping sounds perfectly normal. Newborns always sleep for extensive hours. As far as the spit up and gagging, your newborn could have acid reflux. My son would projectile vomit after eating when he was a week or two old from his reflux. I would call your doctor though concerning the possible side effects of GBS, but my doctor told me if I tested positive and I got thr antibiotic, my son would be safe. But putting in a quick phone call for your reassurance would be worth the 5 minute phone call!