although transnasal endoscopy may well be new technology (the current scope is rather larger than most of our nostrils!) the usual method of esophageal endoscopy is via the mouth.
are you sure you didnt have a FEES/Videofluroscopy test? asked to swallow some cookies and sip water??? there are half a dozen tests along the same lines but id be very impressed if they now use an endoscope through the nose as I think it needs to be at least 13mm diameter to open the gullet up as it moves through. a thin scope through the nose would be more likely to bend and be hard to guide.
im currently having a 24hr PH monitoring and this goes via the nose using a small acid sensing tube.