Biasing signal tubes on a tube power amp/Quicksilver M120

Took possession of a new pair of Quicksilver M120 power amps with the KT150 tube upgrade a few weeks ago, am in the process of break in with about 70 hours so far. About 30 hours in I noticed that a 12AU7 tube had started to flare up when that amp was turned on so swapped that tube to the other amp and it followed the tube, I contacted Quicksilver and he told me that this is not a concern but to please switch that tube back to it's origional amp as the amp was biased for that specific tube, now my question is if I wanted to tube roll these 12AU7 or 12AT7 tubes am I out of luck and what happens when it is time to replace them as they wear out, are my tube rolling days over or are they just limited? What say you?