Many have experienced a higher than normal idle on the 08 bikes with the TBW (throttle by wire) throttles. Some feel it is a problem with the bike but the MOCO is working on a possible fix for this.

It is mainly brought about when the idle is elevated just before shut down such as rolling on the throttle when shutting down, sometimes without knowing or realizing it.
Using the kill switch to shut down when the idle is not at a normal idle will also promote this condition. The ECM remembers the last known idle speed just prior to shut down.

What seems to work for many to eliminate this problem which can also be found in the manual is this procedure below.
It is the same procedure for a replacement of the twist grip sensor as it is to eliminate the stored higher throttle value when shutting down and rolling on the throttle which is what is giving some this problem.

Whenever a new twist grip sensor (or ECM) is installed, place the engine run/stop switch in the RUN position and turn the ignition/light key switch to IGNITION and then back to OFF four times (without starting engine). Allow at least three seconds to elapse between ignition cycles. As the ECM uses the first four ignition cycles to establish the optimum idle speed, there may be initial performance problems if the procedure is not performed, such as high idle or hesitation when the throttle is opened.