One of my liposuction drains just fell out, I was draining below 20 for the past day and a half I believe. Is this normal?

Do not try to reinsert the drain as this can lead to infection! Keep the area clean and contact your surgeon to discuss the situation with them. 

Thank you for the question, but you are early post op and you need to get instruction from your operating plastic surgeon.    Good Luck

most plastic surgeons don't use drains after liposuction alone but might in a patient having a tummy tuck at the same time.  regardless, if the drainage was that low then you should be fine.  see your surgeon in 10 days to be sure you don't have a fluid collection.