Preamp tube came apart?!?

[13strigoi]

I was swapping a tube in an MTS preamp module and when I went to pull the tube out the top half of the glass came off in almost a perfect circle where the lower spacer was. Is this unusual? It was an NOS Tesla so I'm kind of bummed.

[rockon1]

Somewhat unusual but its happened to me too- with a Mullard. I believe heat cycles ,age sometimes get the best of em. Bob

[Blue Strat]

I was swapping a tube in an MTS preamp module and when I went to pull the tube out the top half of the glass came off in almost a perfect circle where the lower spacer was. Is this unusual? It was an NOS Tesla so I'm kind of bummed.

I've seen it happen more often than usual with those particular tubes. The glass may have been thinner than usual.