Noisy static when powering off my Bryston 4B-ST

When I power off my Bryston 4B-ST I can hear very audible static discharge 'crackling" noise.

Is this something to be concerned about?

I've got warranty left on this amp so I assume Bryston will service but wanted to know if this is a sign of a problem with the amp. Seems to work OK otherwise.
My McIntosh 2105 did that when a power supply capacitor was going bad.
A batch of 4b-st went out once upon a time with muting switches that were prone to fail over time. When working, the switch mutes the speaker taps at power down, so that you don't have to listen to the power bleed out through the speakers. I had one that went bad, and it sounds very much like what you're describing. Contact Bryston -- yes, they really are fantastic -- and they'll take care of it.
Ask over at AudioCircle dot com in the Bryston circle. The guy in charge is James Tanner, a VIP honcho at Bryston. he can give you a true answer straight up.