No, one PSI is nothing when you're talking 4 tires...That could be the sun hitting on a tire warming it up.. Get a good gauge, drive you Jeep, let it sit a few hours(cold), then check the pressure. Keep it at what the pounds are on the driver's door sticker. Like Peddler says, it will fluctuate with the temp. Jeeps are no different than any other vehicle when it comes to tire pressures....