I think its on because one of the tires was low on pressure and I believe that there is something in the ecu that defaults the tpms setting to 79psi when the light comes on. That's just a guess from what I have read on some of the forums.
The button in the glove box is only for resisting from a flat tire as far as I can tell. In models after 2010 the button could reset after a low pressure warning. From what I am told only the diagnostics software can turn the light off.