If I were a betting person, I'd guess that the soup was actually sitting at the wrap site and migrated "north". Once lying flat, there was no gravity to hold it there until it trickled into the stomach.
In the beginning there is increasing swelling at the wrap site, and even liquids can get held up there. When they irritate the esophagus, it feels exactly like reflux, since the esophagus is a "dumb organ" and interprets all pain as reflux. Food that ferments as it waits to enter the stomach can be very irritating.
Could you get some reflux early on after surgery? Certainly. The wrap is swollen and can be misshapen, thus letting some reflux though. In addition, surgeons don't attempt to bring reflux to zero...just to "normal levels"...as zero reflux would mean the wrap was too tight to allow food to pass into the stomach.
I remember times early on when I'd burp, and food would regurgitate into my mouth. It wasn't coming from the stomach, but rather the esophagus/wrap site.
It's highly unlikely that you're getting any reflux of a volume that could travel into your nose. During this time healing phase, you might want to continue sleeping with the head of your bed elevated, or at least your upper body. It will give your wrap's swelling time to subside.
Hang in there!
Nissen Fundoplication 2/09
"Whatever you fight, you strengthen, and what you resist, persists.”
“Worry pretends to be necessary but serves no useful purpose”
“Accept - then act. Whatever the present moment contains, accept it as if you had chosen it. Always work with it, not against it.”