Fault Code not registering in memory???

[HYPERR]

I've had the check engine light come on a few times on my 2008 Hypermotard. It does not affect the running of the engine and it goes off after a while. I flicked the gauge toggle lever backwards when the light was on to check the code. It is 23.3EXVL, which is Exhaust Butterfly Valve Error. Since my warranty is up soon, I made an appointment with the dealer to have it looked at even though the light was now off. The dealer stated that there is nothing stored in memory. They did make a note that I came in before the warranty in case of future problems.

Is this normal for a Ducati that an error code is not stored in memory despite it going on a few times?

The nature of this code does not sound really serious and I can clearly hear my butterfly operating. Anyone know what is making the code come on?

[SPPerformance]

Are you sure you can clearly hear the butterfly operating, or can you hear the servo? Is there any chance that you have the cables unhooked? I'm asking because I unhooked my cables at the servo, and occasionally it would throw a code (nothing stored either), but it would clear with a couple of turns of the key. I have since put a limiter on the servo, and have not had another check engine light.