You mentioned authorized dealer, but I didn't want to make too many assumptions that the watch was new. I can tell you, that a lot of watch brands seem to be rushing the watches out of the factories and into stores - since sales have been hot. It does seem that there are more quality control problems - even among higher end brands - than before.
And also, for your power reserve test, you do need to do a more scientific survey. For instance, you may need to put it on a watch winder for a few days (so this way it's likely it's fully wound), then turn off the winder, and see if the watch's power reserve lasts around 72 hours.
If you think you've got a defective watch, I would imagine the authorized dealer will do their part in rectifying the situation - namely sending the watch in on your behalf for warranty work at no expense to you. The other explanation is the watch got magnetized. Surely the authorized dealer mentioned this possibility of the magnetization? Or did they just say "give it more time" and that was it?