I'm hoping it was simply my failure to check all four tire's pressures and not a flat. When I reinstalled the original tire today, I intentionally used the tools that came with the car - did not use my Hydraulic Jack, wrenches, etc. It actually was quite simple, but it took a peek at the Owner's Manual to locate lifting point, etc. (I did use my Torque Wrench to do the final torqueing to 80 foot-lbs.)

 

i had the same thing a couple weeks ago. left the house on a sat morn to run around, got the alarm and light telling my low tire pressure. refilled the tires and found a screw in the tire real close to the sidewall. no one would fix it. had to order a new one that came here on the tuesday after and had the nissan dealership install it since it was closer. those stock 19s have expensive and rare tires. it was kinda nice getting looks of the G at the nissan dealership.