hmm...I have lo-pro tires and sometimes in the RAIN mine will come on or if i corner really fast is will also display on rare occasions...doesn't sound like a small issue because you said you check your tires and we're the same....

might be a stupid question but after it comes on do you reset it? ( in the menu go to reset tire pressure, not just enter. that only ignores it )
cause if you don't its just going to display it again everytime you start the car and drive a few miles