Speedo gauges flickering.

[Limeybastard]

I normally have my cluster lights set to its lowest point when driving at night. Last night when using the electric window switches the luminance ring part of each speedo cluster would flicker when any window switch engaged and windows were already closed.
I'm aware that the load probably would cause slight flicker but the rings would almost flick on and off. It hasn't occured since. Was wondering what it might be?

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