power tube glow when palm muting

[apophis]

I noticed my power tubes increase a bit in their glow when i hit heavy palm mutes on lower strings....i guess its the current increase for handling low frequencies? Or should i worry?? Amp is peavey ultra + ,power tubes winged c 6L6

 

[apophis]

Anyone??

 

[FourT6and2]

Normal.

As long as the tubes aren't red-plating you're fine.