I just finished the adjustment on mine, a little late at 19k miles. All the valves were at the tight end, and several were out of spec, so I replaced all the shims.
I would say if you've got it apart far enough to check the clearance, its not much more work to change out the shims. You simply have to be careful to keep track of which shims go where, and what size you need for replacement. What I do is put each shim in a ziplock sandwich baggie, and mark on the baggie which valve it came from, and the proper size for the replacement. Then take all your baggies to the dealer and get the correct shims.
Its a simple job, just a little tedious, and I would definitely suggest you have a service manual. The only really annoying part of the job is that the wiring harness runs right next to the cam cover on the rear cylinder, making it tough to get the cam cover off and on; and tricky to see that the alignment is correct on the exhaust cam.