Quoting The Blissful Six:" I would contact your Dr. She probably has silent reflux. Glad she's okay...how scarry!"
This is what I was thinking. I would also definitely look into getting an Angel Care movement monitor. They are a tad expensive, but have saved lives, and well worth it IMO. We still use ours, and DS is 10 months old. (Sorry it won't let me post the link)