This is a common question we see for the CS2x0 and CS4x0 products.
On all systems there is a heartbeat indicator on the front left and right sides of the system. On the CS2x0/CS4x0, the heartbeat indicator flashes AMBER. There is nothing wrong with the system at all; only when do any of the bottom LEDs go RED does that indicate a problem with either the left or right controller. This is regardless of the NimbleOS version that you're running.
In the CS300, CS500 and CS700 systems the heartbeat indicators are now GREEN, as you've correctly pointed out, amber can relate to a problem.
Hey Nick - do the LEDs on the two handles correlate to the controller on that side of the array?
You can find the Hardware Guide in the Downloads section of InfoSight, there is a note here indicating that heartbeat color difference. Its a great guide to refer to if you're curious about what all the blinky lights mean.