I think it is not a problem as long as you are relaxed.
I personally keep watching TV or iron some clothes or sit in front of my computer utill I really feel like sleeping. Sometimes untill 1-2 am. It actually helps me a lot to fight nausea caused by air in my stomack. It is much easier and faster to burp it all out when you are vertical. Listen to your body, if it tells you to stand up, stand up... etc.
I did not notice anything going wrong because of that.