You can't really judge a tube by filament brightness unless it is unusually off. Slight variances in alignment as tubes are assembled can make brightness appear to vary between tubes.
The only way to really tell for sure is to put the tube in a tube tester and check the readings.
However, do check your bias settings for each output tube. These can affect brightness and cause problems if they are too far off. If the bias settings are correct, the amp sounds good and the brightness variance isn't just a matter of "slightly" then I'd quit worrying.
As far as the perfect vertical aligment, this doesn't affect performance at all. It is just an appearance issue.
The only way to really tell for sure is to put the tube in a tube tester and check the readings.
However, do check your bias settings for each output tube. These can affect brightness and cause problems if they are too far off. If the bias settings are correct, the amp sounds good and the brightness variance isn't just a matter of "slightly" then I'd quit worrying.
As far as the perfect vertical aligment, this doesn't affect performance at all. It is just an appearance issue.