FWIW Fender has been sourcing octal sockets from Ruby for quite a while now. Maybe 10 years, even longer? So it may not be unusual for other Ruby parts to show up in Fender factory builds.
I'd wait until you have another tank arrive. Maybe the one in that amp is a particularly badly behaved unit.
What I do with "bad actors" like this, aside from dumpsterizing them, is "mummifying" the tank with foam weatherstrip tape. Home Despot sells foam tape that's about 1.5" wide (4.5cm for the rest of the world) intended to keep chilly breezes from blowing into camper backs set atop pickup truck beds. About $10 a roll, enough to cover 3 regular size reverb tanks, top bottom sides front & back. Then a tank "sock" over the whole mess. It's always worked for me, and the tape is good for lots of other applications. If that don't fix it your tank is haunted.