Just about half an hour ago, I'm cruising back to the office, and notice that my TCS OFF indicator was illuminated. I have no idea how this happened, since I didn't turn it off, and I was driving on dry smooth freeway!

Any ideas for things I should check into?

Your Pal,

Mr. C
The King of Dry Ice Esoterica

Here's a little of what our friends to the north have to say about it.
http://www.oqcgp.com/forum/viewtopic.php?t=10218
http://img.photobucket.com/albums/v425/kustomkid54/1998PontiacGrandPrixGTP004.jpg

I would go with a bad hub bearing.

Annnnnnd, it went back out. Hooray! I'll kep an eye on things, to try and figure out what's the dealio.

Did you do anything. Or did it just go away. Those are the one that always come back.
http://img.photobucket.com/albums/v425/kustomkid54/1998PontiacGrandPrixGTP001.jpg

Honestly, it just went away. I'm expecting it to come back :) Hopefully, all will be well till my next commission check comes in!

Good luck.
http://img.photobucket.com/albums/v425/kustomkid54/1998PontiacGrandPrixGTP003.jpg

if any of the 4 ABS sensors fails on the tires it will cause the tcs to fail. By anychance did you changed the break pads recently? Any job that could have disconnected the sensors or soiled them?