jeepgrady said:The alert will not go off until you put more air into the tire. Also, remember that you should not use the numbers on the system in place of an acurate tire guage.
This is the right answer.
I once parked the car outside and it was cold, next day I had the tire pressure warning saying the left rear tire is low, even after driving and warming up the pressure increased but the warning was still indicating low left rear tire.
The only way to get ride of the light and the warining was as Jeepgrady said, I added some air and the light went away.