Steve, Dread's the "go to man" on these issues, but my understanding is that the dreaded (heh, heh) 12th fret hump can be caused by humidity problems. I began having a similar problem with my D10S about a month ago. Two weeks in a hard shell case with a humidifier took care of the problem. I did have to adjust the truss rod after the guitar re-humidified, but no biggie there.

There are a lot of little humidifiers commercially available. I use a home made one that Pike suggested on that "other" forum:



It's just a soap box, with holes drilled in the top, and a damp sponge inside. I would probably give that a shot before looking at adjusting the action.