Tiny blue tone in a valve. Picture inside

[Miracle1980]

Hello, today I have noticed a tiny blue tone in one of my EL34 valves.

I have attached a picture. Everything is fine or should I start worry about?

The valve is not microphonic (tried with a pencil) and everything is working fine...

Thanks

[Latole]

It is some gas into the glass, nothing to worry about .

Google

https://blog.thetubestore.com/understanding-blue-glow-in-your-amp-tubes/

 https://www.thetubestore.com/blue-glow

[AmberB]

The blue glow is normal in some tubes.

[1blueheron]

Is it a blues amp?  Might be it's soul coming out...