After 7 years of EDC, my small Seb has worn a nice little polished groove onto the blade tang from the detente's contact. The detente itself has worn a nice little flat spot on its surface also, but everything functions perfectly--Chris knew what he was doing, as I've had some other folders develop play in the closed position due to similar wear.
What I do is, with the blade 3/4 open (while assembled--not open and locked), drop a drop of lube/oil (I like Militec-1, but like OldDude said, any Teflon-based lube will do and will be long-lasting) between the blade tang and the lockbar in the approximate location of the detente ball. Then work your blade open and closed without necessarily letting it lock open, just enough to work some lube into the crucial area.
Works for me, but YMMV.
Professor.