The TPMS's do not actually have to be on the tires that are installed on the car to affect the "idiot" light on the dash. If the sensors (off the car) are in close enough proximity to the car when parked/garaged for a long enough period of time, the car's computer will still be able to read the sensors as if they're actually installed on the tires that are on the car. The light should return once the car is away from the sensors.Yeah it took me 2 days of driving - short trips - until mine came on. I even checked the invoice to see if they installed TPMS and used the same codes so that it would have to be reprogrammed but they didn't and the light came on a few days later.
It is odd though, and I haven't had the time or care to figure out the pattern, but some days when I turn the car on, the low tire pressure light will blink then after 5 or so minutes it will stay on and then some days it is on and then s tarts blinking after a while.
Regardless I am used to it and it isn't bothering me nearly as much as I thought it would.