None were microphonic initially, as determined by lightly tapping on them with a pencil eraser. Two of them eventually became severely microphonic, however.
Yes Al there are so many that are and owners don’t even know they have them, they think it’s "euphonics" but in fact echo.
I test "every tube" not just 6SN7’s that come by me, with a tap of the fingernail and watching the oscilloscope.
Or in the listening system turn the volume up to normal and get someone to listen in front of the speaker/s while you flick gently with the finger nail.
A "bonk" microphonic, with a "tinkle" can be loose/shaky heater filaments as well.
A "runway" bonk (rotating feedback) that just gets louder and louder, a severely microphonic tube have your spare hand on the poweramp power switch.