My wife just called me and said that the "Tire Pressure" light was showing low pressure. I told her because it's very cold now -5F, it's probably OK to carry on shopping. I'll check the tires when she gets home. Was I right? 
Yes it does affect it, unless they purge the tires of atmospheric air at the factory. The air in the atmosphere still contains moisture. A lot of racers use a closed system to "air up" their tires. It purges the tires, then it fills the tires with nitrogen. Adjusting air pressure isn't an issue, because nitrogen is always kept on hand to run the air tools. Nitrogen is highly compressible. There is a lot of pressure in the bottles that most would assume are typical O² bottles. On typical non-race day during the weekend, we can run all the air tools, and do tire pressure adjustments for practice, on one bottle.When tyres are new they're fitted onto the wheel and would have normal air inside them (dry air is apparently 78% nitrogen), then they'd get pressurised with the pure nitrogen. So is there really much advantage to it- especially if you don't "top them up" with pure nitrogen if the tyre pressure drops?