Let this be a lesson to all who read this. Next time you open the hood, spray some WD40 (or any penetrant) on the nut and the threads. Do so every so often to prevent Supra5MGTE's problem happening to you.
For years, and on numerous used cars, I have saved myself some of these problems by spraying WD40 or Prestone's Silicone spray on various bolts and door locks, hinges, hood and trunk latches, supports, etc.
Did you know that WD40 was invented for the space program to help protect metal?? Yep. Been there, done that (space shuttle that is, 11 years, learned a WHOLE bunch a stuff there, then got laid-off).