CK ALL TIRE PRESSURES EVEN THE SPARE PEOPLE TEND TO FORGET THE SPARE TIRE AT TIMES HAS A SENSOR ALSO. IF THEY ARE ALL AIRED UP SEEK A DIAG AND EST YOU MAY HAVE A BAD SENOR. IF YOU FIND A LOW TIRE DRIVE CAR APPROX 2 MILES AFTERR FILLING AND IT SHOULD RESET
BOTH #1 & #2 are correct. My concern is what you are calling the 'correct pressure'. Are you going by the door jam label/owners manual specs or are you reading the 'max inflation' spec on sidewall of tire. Being over-pressure will cause some TPMS lights to come on , as well as being low.