Mine does it for about 3 seconds every time i start the bike. Bike is brand new, only 300 miles, just figured it was normal.
Just to be clear, there are two levels of fast idle. Assuming the bike is set to idle at 1200rpm normally, the first level of fast idle is around 1800-2000rpm. This one happens every time you start the bike. It is the normal warm up cycle that ensures you don't run the engine to long with cold oil. The next level has to be up around 3000rpm plus+++. It sounds like you are doing 55mph sitting still.
For me, it usually only happens when it is really cold out, but I have had it happen on warm days too. As said above, there seems to be a glitch in the ECM that tells the bike you have suddenly moved to Siberia in January and you need to really rev the engine to warm the oil. I think it is some combination of faulty temp and rpm readings that sets it off. But whatever it is, it can scare the crap out of you the first time it happens. The rpm's are fast enough that if you let out on the clutch, the bike will take off and run on its own at 15-20mph in 1st gear.
As for fixes, there are a few things you can try, but they don't always work.
1 - Let the clutch out just a bit until the transmission starts to engage then pull it back in. Sometimes this will wake up the ECM to realize it is acting like an ass. But more often it just pulls the rpm's from 3000 down to around 2700.
2 - Shut off the engine, turn the key off, wait a few seconds and then restart. This will sometimes fix it completely although you will have to go through the few seconds of normal warm up reving. Other times, it goes right back up to 3-grand.
3 - Ride it out. Pull in the clutch and just let the ECM act like a jerk until the road clears or the light changes to allow you to take off. Usually these fits don't last for more than a minute or two. So if you ride down the road a mile or so, the next time you pull in the clutch you should be back to normal.
4 - Sit and take it. Just stop and wait for the bike to get over the fit which won't take more than a minute or so.
PS- Normally when this happens for me, the bike will start as usual and drop to regular warm up idle. But as I pull out the parking lot or driveway, at the very next stop is when I notice the really high rpm's. Since I ride mostly in town, my next intersection is usually not far enough away for the bike to have warmed up completely. Anyway, if you don't panic, this will be no more than the occasional nuisance. I usually just ride it out.