Installed Wrong Tube 12AX& instead of 12 AT7

I just got a MC275 yesterday and the seller mistakenly installed a 12AX7 into the V4 socket (originally for 12AT7) It didn't sound clipped or it didn't stop functioning except that one channel was louder than the other, but I really don't know if the mistake has damaged the amp, or the damage is slightly and I don't see or hear... I am curious to know if anyone has done the same and what happened... Also, what's most likely is to be damaged if this mistake occurs. What should I look out for... or how do I check. All your inputs will be greatly appreciated.
Shouldn't hurt anything -- based on knowing someone who inadvetently installed all 12 volt tubes in a MC275 in the wrong slots (AX7's into AT7's & vice versa) for an hour or so before the error was caught. McIntosh doesn't push their smaller tubes very hard which probably is a blessing in disquise during situations like this.
12AX7 has more gain than the 12AT7, but is electrically compatible (pinout and voltage/current requirements). No harm done.
Very funny... I might not be a tube-friendly person... all tube hates me. I got a new pair of RCA 12AT7 and one of them didn't light up! I swapped location and it is the tube, not the socket or the circuitry. Again... will a cold (not lighting up) tube create an "lift" or break up in the circuit causing damages due to an incomplete circuitry?