I'm sure you know that generally speaking, other things being equal, you feel the cold more as you get older. We certainly do - a lot more.
Wearing just a base layer and long johns and using a quilt, I'm not surprised you were cold (and no socks?).
Why change clothes to sleep in?. Going by our feedback, that's something novice backpackers do simply because they do it at home, they soon abandon it because it's pointless (unless they are very wet, of course).
Even in our younger hardier days in winter sleeping bags we wore at minimum a cold-weather base layer and winter weight fleece, along with Powerstretch tights and walking trousers (and our walking socks). These were the clothes we had been walking in that day, minus any shell layer. On the very coldest summit nights (around -14º) we wore a lightweight down jacket on top.
What model of NeoAir was it?. If it was the standard Xlite, that wouldn't help matters, in those temperatures the Xtherm is in order. Even if you didn't directly feel cold from below, that might be just a perception and it's still a weak point in the heat retention system.
Quilts might be ok for the summer months, but in cold weather it's a bag every time and a good one at that. It ensures you are completely encased no matter how you move in the night, and insulation works better when it gently hugs the body all over. Your head should also be well insulated by the bag hood.
Our experience tells us that if you reach the point where you feel cold around the torso in the night, it's very difficult to get warm again without some
input of heat, most conveniently a hot drink. Some rapid energy input could help, we always carry Dextrose lozenges for a quick boost.