Its sort of normal I guess... but if the regulator is doing its job it the lights will not dim. RPMs should not effect light brightness

I usually rework the electrical system when I see this

 

Hard to tell with the HID headlights because they use less voltage. but i've already thought this was normal.

My hong kong LED turn signals clearly pulse at idle and brighten up as soon as i blip the throttle. Has done this as long as i've had the bike.

 

Paid close attention to mine this morning while warming up. When cold and with fast idle, lights do not dim with low or low/high on. With the bike warmed up at normal idle, no dim with just low beam and a minor dimming with both low/high on. Battery cranks fine on startup also. It has done this since I got the bike (4 months/3K miles). Seems to be normal operation as Sprock suggests, but I will check the electrical this weekend for peace of mind.

 

FYI

I fix 3 or 4 of these a month in the summer...