I was playing around in creative and trying to see how fast I can get the beacons beam to "blink" (change colors) using Cyan Glass and Black glass. I set up the timers to issue pulses to each of the pistons pushing a block of stained glass one way or the other. When the pistons pushed the glass just as the beam's color updates, the beam went white, instead of the color it's supposed to be. The entire setup can be seen in the images I've attached