I have no idea what caused this, but as of yesterday or the day before, when I press ESC, the = key seems to be pressed instead. This happens across all programs. And it doesn't seem like the ESC key has been remapped (if this is the proper term) to be =, but that my computer is recognizing a press of ESC as a press of =. For instance, when I have the "Keyboard Layout Chart" up on my screen and I press ESC, = lights up orange. All other keys are working correctly.
Any thoughts on what happened or how to fix it? Is my keyboard just going bad? (The laptap is about 8 years old.)
I have Ubuntu 14.10.
EDIT: My keyboard seems to be fine, at least physically. I followed Fabby's directions (thanks!) and got 0x01 0x81 after pressing ESC.