snapping sound on startup

[Neuronal]

i was on vacation for a couple weeks, and when I came back and flipped my paramount v1.0 on I heard a loud fast snap coming from the amp (nothing through speakers). I shut it down, looked at it (fine) and took resistances, which were fine, and then when I turned back it on it was totally ok (and still is after several power cycles). Is it possible that the tube arced or something like that? My wife has been teasing me about the tube "farting" because I told her maybe some air that leaked in or something. Is that actually a thing? Anything else I should check? Thanks for the advice!

[Paul Birkeland]

Is this a 2A3 or 300B Paramount?

[Neuronal]

300B with stock EH tube

[Paul Birkeland]

It's pretty tough to know.  If the silver coating on the 300B on that side has any white coloration to it, you could have a gassy tube.