Scott,
afaik AA uses Trent 800s.
The question behind my question was whether during the certification process engineers assumed a higher degree of syncronization and thus less vibration than the industry is achieving in the present economic climate.
I have no expertise but can imagine valid reasons for engine life being extended, thus setting up for bigger differences between a 'new' engine and one nearing end of (a longer) service period.
It's just as likely that nothing has changed and I suddenly noticed it. Probably no big deal if the airframe doesn't mind.
pj