Recently, My RDX' 13 is asking for tire pressure verification. They have N2. Why

Nitrogen , for the most part is a lovely scam. Your tire pressures should be set , when cooled down(generally after sitting overnight ), to the pressure SPECIFIED ON THE DOOR JAM LABEL for front and rear(may be different) COLD pressure. It is NORMAL (heat expands/cool contracts) for the pressure to fluctuate from driving. IF the low pressure light comes on , and goes off after a few miles of driving , then I would suggest either the gauge being used is incorrect , the set pressure is incorrect, or it has a different issue that may need professional diagnosis.