Revved Engine When Pressing The Clutch To Change Into Neutral.

Does the neutral indication come on immediately when you select neutral? I'm wondering if you have a dodgy neutral sensor and the ECU thinks the bike is still in gear and so is revving the engine to stop it stalling when you release the clutch.

I have a different Triumph (a 1200cc twin) but the other day I noticed that easing out the clutch when stationary in first gear made the engine rev even though I wasn't giving it any throttle, I could use it to inch the bike forward.